Sunlands Technology (STG) 20-F 26 Apr 19 2018 FY Annual report (foreign) Financial data

Document and Entity Information

Document and Entity Information	12 Months Ended
	Dec. 31, 2018shares
Document Type	20-F
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	STG
Entity Registrant Name	Sunlands Technology Group
Entity Central Index Key	0001723935
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Shell Company	false
Document - Document and Entity Information [Line Items]
Document Type	20-F
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	STG
Entity Registrant Name	Sunlands Technology Group
Entity Central Index Key	0001723935
Current Fiscal Year End Date	--12-31
Class A Ordinary Shares
Entity Common Stock, Shares Outstanding	1,773,301
Class B Ordinary Shares
Entity Common Stock, Shares Outstanding	826,389
Class C Ordinary Shares
Entity Common Stock, Shares Outstanding	4,265,286

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS ¥ in Thousands, $ in Thousands	Dec. 31, 2018CNY (¥)	Dec. 31, 2018USD ($)	Dec. 31, 2017CNY (¥)
Current assets
Cash and cash equivalents	¥ 1,248,810	$ 181,632	¥ 559,459
Short-term investments	1,028,564	149,598	353,070
Prepaid expenses and other current assets	124,908	18,169	48,993
Amounts due from related parties			250,096
Deferred costs, current	180,657	26,275	55,073
Total current assets	2,582,939	375,674	1,266,691
Non-current assets
Property and equipment, net	559,511	81,377	525,288
Intangible assets, net	1,369	199	1,552
Deferred costs, non-current	146,610	21,324	43,187
Long-term investments	30,009	4,365	3,300
Other non-current assets	418,700	60,897	129,641
Total non-current assets	1,156,199	168,162	702,968
TOTAL ASSETS	3,739,138	543,836	1,969,659
Current liabilities
Accrued expenses and other current liabilities (including accrued expenses and other current liabilities of the consolidated VIEs without recourse to Sunlands Technology Group of RMB223,298 and RMB241,204 as of December 31, 2017 and 2018, respectively)	455,284	66,218	235,900
Deferred revenue, current (including deferred revenue, current of the consolidated VIEs without recourse to Sunlands Technology Group of RMB1,325,954 and RMB1,765,085 as of December 31, 2017 and 2018, respectively)	1,765,085	256,721	1,325,954
Payables to acquire buildings (including payables to acquire buildings of the consolidated VIEs without recourse to Sunlands Technology Group of RMB180,390 and nil as of December 31, 2017 and December 31, 2018, respectively)	61,540	8,951	240,390
Long-term debt, current portion (including long-term debt, current portion of the consolidated VIEs without recourse to Sunlands Technology Group of nil and nil as of December 31, 2017 and December 31, 2018, respectively)	32,500	4,727
Total current liabilities	2,314,409	336,617	1,802,244
Non-current liabilities
Deferred revenue, non-current (including deferred revenue, non-current of the consolidated VIEs without recourse to Sunlands Technology Group of RMB784,474 and RMB1,520,940 as of December 31, 2017 and 2018, respectively)	1,520,940	221,212	784,474
Other non-current liabilities (including other non-current liabilities of the consolidated VIEs without recourse to Sunlands Technology Group of nil and RMB135 as of December 31, 2017 and December 31, 2018, respectively)	17,147	2,494
Long-term debt, non-current portion (including long-term debt, non-current portion of the consolidated VIEs without recourse to Sunlands Technology Group of nil and nil as of December 31, 2017 and December 31, 2018, respectively)	225,625	32,816
Total non-current liabilities	1,763,712	256,522	784,474
TOTAL LIABILITIES	4,078,121	593,139	2,586,718
MEZZANINE EQUITY
TOTAL MEZZANINE EQUITY			1,024,709
COMMITMENTS AND CONTINGENCIES (Note 20)
SHAREHOLDERS’ DEFICIT
Ordinary shares			1
Treasury stock	0	0	0
Additional paid-in capital	2,391,822	347,876	289,674
Accumulated other comprehensive (loss)/income	118,827	17,283	(8,759)
Accumulated deficit	(2,849,770)	(414,482)	(1,922,748)
Total Sunlands Technology Group shareholders’ deficit	(339,119)	(49,323)	(1,641,832)
Noncontrolling interest	136	20	64
TOTAL SHAREHOLDERS’ DEFICIT	(338,983)	(49,303)	(1,641,768)
TOTAL LIABILITIES, MEZZANINE EQUITY AND SHAREHOLDERS’ DEFICIT	3,739,138	543,836	1,969,659
Series A Convertible Redeemable Preferred Shares
MEZZANINE EQUITY
TOTAL MEZZANINE EQUITY			292,000
Series B Convertible Redeemable Preferred Shares
MEZZANINE EQUITY
TOTAL MEZZANINE EQUITY			601,605
Series B+ Convertible Redeemable Preferred Shares
MEZZANINE EQUITY
TOTAL MEZZANINE EQUITY			131,104
Class A Ordinary Shares
SHAREHOLDERS’ DEFICIT
Ordinary shares	1
TOTAL SHAREHOLDERS’ DEFICIT	1
Class B Ordinary Shares
SHAREHOLDERS’ DEFICIT
Ordinary shares	0	$ 0	¥ 0
Class C Ordinary Shares
SHAREHOLDERS’ DEFICIT
Ordinary shares	1
TOTAL SHAREHOLDERS’ DEFICIT	¥ 1

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) ¥ in Thousands, $ in Thousands	Dec. 31, 2018CNY (¥)shares	Dec. 31, 2018USD ($)$ / sharesshares	Mar. 31, 2018shares	Dec. 31, 2017CNY (¥)shares	Dec. 31, 2017$ / shares	Sep. 18, 2015$ / sharesshares	Sep. 18, 2015¥ / sharesshares
Accrued expenses and other current liabilities	¥ 455,284	$ 66,218		¥ 235,900
Deferred revenue, current	1,765,085	256,721		1,325,954
Payables to acquire buildings	61,540	8,951		240,390
Long-term debt, current	32,500	4,727
Deferred revenue, non-current	1,520,940	221,212		¥ 784,474
Other non-current liabilities	17,147	2,494
Long-term debt, non-current	¥ 225,625	$ 32,816
Ordinary shares, par value | (per share)		$ 0.00005			$ 0.00005	$ 0.00005	¥ 0.0003
Ordinary shares, shares authorized	1,000,000,000	1,000,000,000		1,000,000,000		1,000,000,000	1,000,000,000
Ordinary shares, shares issued				4,329,000		1	1
Ordinary shares, shares outstanding			4,329,000	4,329,000
Class A Ordinary Shares
Ordinary shares, par value | $ / shares		$ 0.00005			0.00005
Ordinary shares, shares authorized	796,062,195	796,062,195		796,062,195
Ordinary shares, shares issued	1,818,383	1,818,383
Ordinary shares, shares outstanding	1,773,301	1,773,301	63,714
Class B Ordinary Shares
Ordinary shares, par value | $ / shares		$ 0.00005			0.00005
Ordinary shares, shares authorized	826,389	826,389		826,389
Ordinary shares, shares issued	826,389	826,389
Ordinary shares, shares outstanding	826,389	826,389
Class C Ordinary Shares
Ordinary shares, par value | $ / shares		$ 0.00005			$ 0.00005
Ordinary shares, shares authorized	203,111,416	203,111,416		203,111,416
Ordinary shares, shares issued	4,265,286	4,265,286
Ordinary shares, shares outstanding	4,265,286	4,265,286	4,265,286
VIEs
Accrued expenses and other current liabilities | ¥	¥ 241,204			¥ 223,298
Deferred revenue, current | ¥	1,765,085			1,325,954
Payables to acquire buildings | ¥				180,390
Deferred revenue, non-current | ¥	1,520,940			¥ 784,474
Other non-current liabilities | ¥	¥ 135

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS ¥ in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2018CNY (¥)¥ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017CNY (¥)¥ / sharesshares	Dec. 31, 2016CNY (¥)¥ / sharesshares
Income Statement [Abstract]
Net revenues		¥ 1,973,985	$ 287,104	¥ 970,162	¥ 418,910
Cost of revenues (including share-based compensation expenses of nil, RMB19,244 and RMB314 for the years ended December 31, 2016, 2017 and 2018, respectively)		(330,376)	(48,051)	(170,261)	(70,986)
Gross profit		1,643,609	239,053	799,901	347,924
Operating expenses
Sales and marketing expenses (including share-based compensation expenses of nil, RMB75,237 and RMB773 for the years ended December 31, 2016, 2017 and 2018, respectively)		(2,152,830)	(313,116)	(1,351,811)	(503,643)
Product development expenses		(76,022)	(11,057)	(32,862)	(13,932)
General and administrative expenses (including share-based compensation expenses of nil, RMB194,282 and RMB2,764 for the years ended December 31, 2016, 2017 and 2018, respectively)		(443,691)	(64,532)	(342,906)	(89,390)
Total operating expenses		(2,672,543)	(388,705)	(1,727,579)	(606,965)
Loss from operations		(1,028,934)	(149,652)	(927,678)	(259,041)
Interest income		70,355	10,232	13,578	3,051
Interest expense		(2,171)	(316)
Other income, net		32,090	4,667	276	2,423
Loss before income tax expenses		(928,660)	(135,069)	(913,824)	(253,567)
Income tax expenses		0	0	0	0
(Loss)/gain from equity method investments		1,710	249	(4,890)
Net loss		(926,950)	(134,820)	(918,714)	(253,567)
Less: Net (loss)/gain attributable to noncontrolling interest		72	10	(136)
Net loss attributable to Sunlands Technology Group		¥ (927,022)	$ (134,830)	¥ (918,578)	¥ (253,567)
Net loss per share attributable to ordinary shareholders of Sunlands Technology Group:
Basic and diluted | (per share)		¥ (147.27)	$ (21.42)	¥ (232.80)	¥ (66.40)
Weighted average shares used in calculating net loss per ordinary share:
Basic and diluted	[1]	6,294,870	6,294,870	3,945,864	3,818,618
[1]	Each 25 American depositary shares ("ADSs") represents one of the Company's Class A ordinary shares.

CONSOLIDATED STATEMENTS OF OP_2

CONSOLIDATED STATEMENTS OF OPERATIONS (Parenthetical) - CNY (¥) ¥ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allocated Share-based Compensation Expense	¥ 3,851	¥ 288,763
Cost of Revenues
Allocated Share-based Compensation Expense	314	19,244	¥ 0
Selling and Marketing Expense
Allocated Share-based Compensation Expense	773	75,237	0
General and Administrative Expense
Allocated Share-based Compensation Expense	¥ 2,764	¥ 194,282	¥ 0

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018CNY (¥)	Dec. 31, 2018USD ($)	Dec. 31, 2017CNY (¥)	Dec. 31, 2016CNY (¥)
Statement Of Income And Comprehensive Income [Abstract]
Net loss	¥ (926,950)	$ (134,820)	¥ (918,714)	¥ (253,567)
Other comprehensive (loss)/income, net of tax effect of nil:
Change in cumulative foreign currency translation adjustments	127,586	18,557	(8,759)
Total comprehensive loss	(799,364)	(116,263)	(927,473)	(253,567)
Less: comprehensive (loss)/income attributable to noncontrolling interest	72	10	(136)
Comprehensive loss attributable to Sunlands Technology Group	¥ (799,436)	$ (116,273)	¥ (927,337)	¥ (253,567)

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' DEFICIT ¥ in Thousands, $ in Thousands		CNY (¥)shares	USD ($)shares	Class A Ordinary SharesCNY (¥)shares	Class B Ordinary Sharesshares	Class C Ordinary SharesCNY (¥)shares	Ordinary SharesCNY (¥)shares	Additional Paid-in CapitalCNY (¥)	Additional Paid-in CapitalUSD ($)	Treasury Stockshares	Accumulated Other Comprehensive (Loss)/IncomeCNY (¥)	Accumulated Other Comprehensive (Loss)/IncomeUSD ($)	Accumulated DeficitCNY (¥)	Accumulated DeficitUSD ($)	Total Sunlands Technology Group Shareholders' DeficitCNY (¥)	Total Sunlands Technology Group Shareholders' DeficitUSD ($)	Noncontrolling InterestCNY (¥)	Noncontrolling InterestUSD ($)
Balances at Dec. 31, 2015		¥ (371,744)					¥ 1	¥ 911					¥ (372,656)		¥ (371,744)
Balances (in shares) at Dec. 31, 2015 | shares							3,818,618
Net loss for the year		(253,567)											(253,567)		(253,567)
Recapitalization in connection with the Group’s 2016 reorganization (Note 1)		(293,644)											(293,644)		(293,644)
Capital contribution from equity shareholders		30,000						30,000							30,000
Balances at Dec. 31, 2016		(888,955)					¥ 1	30,911					(919,867)		(888,955)
Balances (in shares) at Dec. 31, 2016 | shares							3,818,618
Net loss for the year		(918,714)											(918,578)		(918,578)		¥ (136)
Capital contribution from a noncontrolling shareholder		200															200
Repurchase of equity from shareholders	[1]	(71,303)						(30,000)					(41,303)		(71,303)
Cash dividend to a Series A convertible redeemable preferred shareholder (Note 13)		(43,000)											(43,000)		(43,000)
Shares issuance in relation to share-based compensation (Note 16), shares | shares							510,382
Share-based compensation		288,763						288,763							288,763
Foreign currency translation adjustments		(8,759)									¥ (8,759)				(8,759)
Balances at Dec. 31, 2017		¥ (1,641,768)					¥ 1	289,674			(8,759)		(1,922,748)		(1,641,832)		64
Balances (in shares) at Dec. 31, 2017 | shares		4,329,000	4,329,000				4,329,000
Net loss for the year		¥ (926,950)	$ (134,820)										(927,022)		(927,022)		72
Issuance of ordinary shares, net of issuance cost of 80,128		1,109,517						1,109,517							1,109,517
Issuance of ordinary shares, net of issuance cost, shares | shares				659,131
Conversion of convertible redeemable preferred shares upon initial public offering (Note 14)		1,024,709		¥ 1		¥ 1	¥ (1)	1,024,708							1,024,709
Conversion of convertible redeemable preferred shares upon initial public offering (Note 14), shares | shares				1,159,252	826,389	4,265,286	(4,329,000)
Share repurchase		(34,828)						(34,828)							(34,828)
Share repurchase, shares | shares				(45,082)						45,082
Share-based compensation		2,751						2,751							2,751
Foreign currency translation adjustments		127,586	18,557								127,586				127,586
Balances at Dec. 31, 2018		¥ (338,983)	$ (49,303)	¥ 1		¥ 1		¥ 2,391,822	$ 347,876		¥ 118,827	$ 17,283	¥ (2,849,770)	$ (414,482)	¥ (339,119)	$ (49,323)	¥ 136	$ 20
Balances (in shares) at Dec. 31, 2018 | shares				1,773,301	826,389	4,265,286				45,082
[1]	In July 2017, Beijing Shangde Online Education Technology Co., Ltd. (“Beijing Sunlands”) repurchased equity interests held by certain shareholders at a total cash consideration of RMB71,303. Such equity interests of Beijing Sunlands were originally acquired at a cost of RMB30,000.

CONSOLIDATED STATEMENTS OF CH_2

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' DEFICIT (Parenthetical) ¥ in Thousands	1 Months Ended
	Jul. 31, 2017CNY (¥)
Beijing Sunlands
Repurchased equity interests	¥ 71,303
Cost of acquired stock	¥ 30,000

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASHFLOWS ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018CNY (¥)	Dec. 31, 2018USD ($)	Dec. 31, 2017CNY (¥)	Dec. 31, 2016CNY (¥)
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	¥ (926,950)	$ (134,820)	¥ (918,714)	¥ (253,567)
Adjustments to reconcile net loss to net cash generated from operating activities:
Share-based compensation	3,851	560	288,763
Depreciation and amortization	25,778	3,749	8,109	5,470
Loss on disposal of property and equipment			120
Loss/(gain) from equity method investments	(1,710)	(249)	4,890
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(92,291)	(13,420)	(30,222)	3,139
Deferred costs	(229,007)	(33,308)	(73,032)	(14,058)
Other non-current assets	(4,286)	(623)	(7,480)	(914)
Accrued expenses and other current liabilities	214,697	31,226	164,245	35,710
Deferred revenue	1,175,597	170,983	1,382,859	313,492
Other non-current liabilities	14,864	2,162
Net cash generated from operating activities	180,543	26,260	819,538	89,272
CASH FLOWS FROM INVESTING ACTIVITIES
Purchase of short-term investments	(4,352,103)	(632,987)	(2,139,097)	(858,500)
Proceeds from maturity of short-term investments	3,708,810	539,424	1,931,027	757,500
Acquisition of property and equipment	(517,763)	(75,306)	(398,190)	(15,871)
Acquisition of intangible assets	(665)	(97)	(746)	(824)
Consideration paid for a business acquisition, net of cash received of 301			(699)
Payment for equity method investments	(25,000)	(3,636)	(8,190)
Net cash used in investing activities	(1,186,721)	(172,602)	(615,895)	(117,695)
CASH FLOWS FROM FINANCING ACTIVITIES
Amounts due from related parties	253,672	36,895	7,944	(276)
Amounts due to a related party				(24,000)
Capital contribution from Series B and B+ convertible redeemable preferred shareholders			732,709
Capital contribution from a noncontrolling shareholder			200
Recapitalization in connection with the Group’s 2016 reorganization				(293,644)
Capital contribution (withdrew) from Series A convertible redeemable preferred shareholders			(285,078)	335,000
Capital contribution (withdrew) from equity shareholders			(30,000)	30,000
Repurchase of equity from shareholders			(41,303)
Cash dividend to a Series A convertible redeemable preferred shareholder			(43,000)
Proceeds from initial public offering, net of issuance cost of 80,128	1,109,517	161,373
Payment for share repurchase	(33,971)	(4,941)
Proceeds from bank loan	260,000	37,815
Repayment of bank loan	(1,875)	(273)
Net cash generated from financing activities	1,587,343	230,869	341,472	47,080
Effect of exchange rate changes	108,186	15,735	(8,759)
Net increase in cash and cash equivalents	689,351	100,262	536,356	18,657
Cash and cash equivalents at beginning of the year	559,459	81,370	23,103	4,446
Cash and cash equivalents at end of the year	1,248,810	181,632	559,459	23,103
Supplemental schedule of non-cash investing activities:
Payables for leasehold improvement and intangible assets	7,194	1,046	2,180	¥ 1,902
Payables to acquire buildings	61,540	8,951	¥ 240,390
Supplemental disclosure of cash flow information:
Interest paid	¥ 1,099	$ 160

CONSOLIDATED STATEMENTS OF CA_2

CONSOLIDATED STATEMENTS OF CASHFLOWS (Parenthetical) ¥ in Thousands	12 Months Ended
	Dec. 31, 2017CNY (¥)
Statement Of Cash Flows [Abstract]
Cash received on business acquisition	¥ 301
Stock issuance costs	¥ 80,128

Organization and Basis of Prese

Organization and Basis of Presentation	12 Months Ended
	Dec. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization and Basis of Presentation	1. ORGANIZATION AND BASIS OF PRESENTATION Sunlands Technology Group (the “Company” or “Sunlands Technology”), formerly known as Sunlands Online Education Group, was incorporated under the laws of the Cayman Islands on September 18, 2015. The Company, its subsidiaries, its consolidated variable interest entities (“VIEs”) and VIEs’ subsidiaries (collectively the “Group”) are primarily engaged in providing online education service in the People’s Republic of China (“PRC” ). History of the Group In July 2011, Mr. Jianhong Yin (the “Founder”) established Sunland Education Co. Limited (the “Previous Cayman”). In March 2012, the Previous Cayman, through its 100% owned subsidiary, Sunland Education Technology HK Limited, established Beijing Shangzhi Jiaye Education Technology Co., Ltd. (the “Previous WFOE”). PRC laws and regulations currently require any foreign entity that invests in the education business in China to be an educational institution with relevant experience in providing education services outside China. To comply with the PRC laws and regulations, the Founder, Previous WFOE and Beijing Shangde Jiaxun Education Technology Co., Ltd. (“Shangde Jiaxun” or the “Previous VIE”), which was established by the Founder in July 2008, entered into a series of contractual arrangements in December 2013 (the “Previous VIE arrangement”). As a result of these contractual arrangements, the Previous Cayman believed that these contractual arrangements would enable itself to (1) have power to direct the activities that most significantly affects the economic performance of the Previous VIE, and (2) receive the economic benefits of the VIE that could be significant to the Previous VIE. Accordingly, the Previous Cayman was considered the primary beneficiary of the Previous VIE and was able to consolidate the Previous VIE and its subsidiaries. In June 2014, the Group determined to cease the offline, classroom-based education service and transform its business model to online education service. During 2015 and 2016, in order to execute the business shift and prepare for an initial public offering (“IPO”) in the PRC, the Group terminated the Previous VIE arrangement and started to conduct the online education service through Beijing Shangde Online Education Technology Co., Ltd. (the “2016 Reorganization”). Beijing Sunlands was set up by Shangde Jiaxun in September 2013 as a limited liability company in the PRC. In August 2017, the Group decided to pursue the IPO in the capital market overseas. To accommodate the aforementioned restrictions, the Group identified the Company as the prospective listing entity and entered into a series of contractual arrangements among the Company’s shareholders, its subsidiaries, the Founder, the Chief Executive Officer (the “CEO”) of the Group, Beijing Sunlands and the shareholders of Beijing Sunlands (the “2017 Reorganization”). 2016 Reorganization During 2015 and 2016, in part of the IPO plan in the PRC, the Group undertook a series of steps, mainly to dissolve the VIE structure, which includes: • During 2015, the Previous WFOE terminated the Previous VIE arrangement through which RMB49,359 was recognized as an effect of such reorganization in the Group’s consolidated statements of changes in shareholders’ deficit. Meanwhile, Shangde Jiaxun, the Previous VIE, transferred its equity interests in Beijing Sunlands to the Founder and the CEO. • From March to July 2016, based on the VIE termination agreement entered into by the shareholders of the Previous WFOE, Beijing Sunlands acquired 100% equity interests of the Previous WFOE at a cash consideration of RMB293,644. Such cash consideration was used by the Previous Cayman to repurchase the equity interests held by the third party investors of the Previous Cayman. • Subsequent to the repurchase, the shareholders of the Previous Cayman made capital contributions to Beijing Sunlands. After that, the shareholders of the Previous Cayman became the shareholders of Beijing Sunlands. 1. ORGANIZATION AND BASIS OF PRESENTATION - continued 2016 Reorganization- continued As the Previous Cayman, Previous WFOE and Beijing Sunlands were all under common control of the Founder, the above series of steps to reorganize the Group during 2015 and 2016 were accounted for in a manner similar to a pooling of interest with assets and liabilities and were all reflected at their historical amounts in the Group’s consolidated financial statements. 2017 Reorganization In August 2017, the Group decided to pursue the IPO in the capital market overseas. Accordingly, the Group undertook a series of steps, mainly to establish the VIE structure, which includes: • In August 2017, the Company, through its wholly-owned subsidiary, Sunlands Online Education HK Limited (formerly known as Studyvip Online Education HK Limited) (“Sunlands HK”), established Wuhan Studyvip Online Education Co., Ltd. (“Wuhan Zhibo” or the “New WFOE”). • In August 2017, the New WFOE entered into a series of contractual agreements with Beijing Sunlands (the “New VIE”), its subsidiaries and the shareholders of Beijing Sunlands (the “New VIE arrangements”). The Group believes that these contractual arrangements would enable the Company to (1) have power to direct the activities that most significantly affect the economic performance of the New VIE, and (2) receive the economic benefits of the VIE that could be significant to the New VIE. Accordingly, the Company is considered the primary beneficiary of the New VIE and is able to consolidate the New VIE and its subsidiaries. As the Company, New WFOE and New VIE were all under common control of the Founder, the above series of steps to reorganize the Group during 2017 were accounted for in a manner similar to a pooling of interest with assets and liabilities at their historical amounts in the Group’s consolidated financial statements. As such, the Group’s consolidated financial statements were prepared as if the current corporate structure had been in existence for all periods presented. In March 2018, the Founder and the CEO set up a new limited company, Tianjin Shangde Online Education Technology Co., Ltd. (“Tianjin Shangde”) to operate online education services. Subsequently, in May 2018, Tianjin Studyvip Education Co., Limited (“Tianjin Sunlands"), a wholly-owned subsidiary of the Group, entered into a series of contractual arrangements with Tianjin Shangde, and the shareholders of Tianjin Shangde, through which the Company obtained effective control over, and became the primary beneficiary of, Tianjin Shangde. 1. ORGANIZATION AND BASIS OF PRESENTATION - continued 2017 Reorganization - continued As of December 31, 2018, details of the Company’s subsidiaries, its VIEs and VIEs’ subsidiaries were as follows: Name (1) Date of establishment/ acquisition Place of establishment Percentage of direct or indirect economic ownership Principal activities Subsidiaries: Sunlands HK October 6, 2015 HongKong 100% Investment holding Wuhan Zhibo August 2, 2017 PRC 100% Provision of technical consultation and services Tianjin Sunlands July 31, 2017 PRC 100% Provision of technical consultation and services Variable interest entities ("VIEs"): Beijing Sunlands September 27, 2013 PRC N/A* Investment holding and provision of education services Tianjin Shangde March 21, 2018 PRC N/A* Provision of education services VIEs’ subsidiaries: Beijing Shangzhi Jiaye Education Technology Co., Ltd. March 13, 2012 PRC 100% Provision of education services Beijing Shangren Chongye Education Technology Co., Ltd. September 27, 2013 PRC 100% Provision of education services Guangdong Shangde Online Education Technology Co., Ltd. October 15, 2013 PRC 100% Provision of education services Urumchi Shangde Renye Business Consulting Co., Ltd. March 10, 2015 PRC 100% Provision of education services Guangzhou Youhe Self-study Training School May 19, 2015 PRC 100% Provision of education services Beijing Bainiao Education Technology Co., Ltd. (2) March 3, 2016 PRC 100% Provision of education services Shanghai Shangchi Education Technology Co., Ltd. December 22, 2016 PRC 90% Provision of education services Beijing Shangren Side Education Technology Co., Ltd. June 2, 2017 PRC 100% Provision of education services Shanghai Shangchi Institute September 1, 2017 PRC 100% Provision of education services Guangzhou Shangzhi Side Education Technology Co., Ltd. September 28, 2017 PRC 100% Provision of education services * These entities are controlled by the Company pursuant to the contractual agreements disclosed below. (1) The English names are for identification purpose only. (2) Previously known as Beijing Shangren Chongde Education Technology Co., Ltd. The name change permit was granted by governmental authority on June 29, 2018. 1. ORGANIZATION AND BASIS OF PRESENTATION - continued The VIE arrangements There are some uncertainties as to whether applicable PRC laws and regulations prohibit foreign investors from providing telecommunications value-added services in the PRC. As a Cayman Islands corporation, the Company is deemed a foreign legal person under PRC laws. Accordingly, Wuhan Zhibo and Tianjin Sunlands, the Company’s wholly owned subsidiaries in the PRC, as foreign invested companies, may be deemed to be a telecommunications value-added services provider in the PRC. To comply with these foreign ownership restrictions, the Company operates substantially all of its online education services through its VIEs, Beijing Sunlands and Tianjin Shangde, and their subsidiaries, in the PRC. Through the below contractual agreements, Wuhan Zhibo and Tianjin Sunlands have (1) the power to direct the activities of the VIEs and their subsidiaries that most significantly affect their economic performance and (2) the right to receive substantially all the benefits from the VIEs and their subsidiaries. They are therefore considered the primary beneficiaries of the VIEs and their subsidiaries, and accordingly, the results of operations, assets and liabilities of the VIEs and their subsidiaries are consolidated in the Group's financial statements . • Agreements that transfer economic benefits to the Company Exclusive Technical Consultation and Service Agreement Under the exclusive technical consultation and service agreement among Wuhan Zhibo, and Beijing Sunlands and its subsidiaries, Wuhan Zhibo has the exclusive right to provide, among other things, technical consultation and services to Beijing Sunlands and Beijing Sunlands Subsidiaries, and Beijing Sunlands and Beijing Sunlands Subsidiaries agree to accept all the consultation and services provided by Wuhan Zhibo. Without Wuhan Zhibo’s prior written consent, Beijing Sunlands and Beijing Sunlands Subsidiaries are prohibited from engaging any third party to provide any services contemplated by this agreement. In addition, Wuhan Zhibo has exclusive and proprietary ownership, rights and interests in any and all intellectual properties arising out of or created during the performance of this agreement. Beijing Sunlands and Beijing Sunlands Subsidiaries agree to pay a quarterly service fee to Wuhan Zhibo at an aggregate amount of a certain percentage ranging from 10% to 100% of Beijing Sunlands and Beijing Sunlands Subsidiaries’ monthly revenue. Unless terminated by Wuhan Zhibo, this agreement will remain effective until the dissolution of Beijing Sunlands and Beijing Sunlands Subsidiaries. Without Wuhan Zhibo’s prior written consent, Beijing Sunlands and Beijing Sunlands Subsidiaries do not have the right to terminate this exclusive technical consultation and service agreement. Tianjin Sunlands, Tianjin Shangde and its subisidiaries have entered into an Exclusive Technical Consultation and Service Agreement on May 21, 2018, the terms of which are substantially the same as the agreement of Beijing Sunlands summarized above. Business Operation Agreement Under the business operation agreement each of Beijing Sunlands, Beijing Sunlands Subsidiaries and the shareholders of Beijing Sunlands confirmed and agreed that, without Wuhan Zhibo’s prior written consent, it shall not make any transaction that has a material adverse effect on the assets, business, personnel, obligations, rights or operations of Beijing Sunlands and Beijing Sunlands Subsidiaries, including but not limited to sale or purchase of any assets or rights exceeding RMB50, incurrence of any encumbrance on any of its assets, including intellectual property rights, in favor of a third party, amendment of its articles of association or business scope, or change of its normal operation procedures. Beijing Sunlands, Beijing Sunlands Subsidiaries and the shareholders of Beijing Sunlands shall accept and execute opinions and instructions of Wuhan Zhibo in connection with the employee engagement and dismissal, daily operations and financial management systems. The shareholders of Beijing Sunlands shall elect or appoint the candidates recommended by Wuhan Zhibo as Beijing Sunlands’ directors and supervisors, and procure the appointment of Beijing Sunlands’ chairman of the board and senior management pursuant to Wuhan Zhibo’s designation. The agreement also provides that if any of the agreements among Wuhan Zhibo, Beijing Sunlands and the Beijing Sunlands Subsidiaries is terminated, Wuhan Zhibo is entitled to terminate all of the other agreements among itself, Beijing Sunlands and Beijing Sunlands Subsidiaries. This agreement will remain binding until dissolution of Beijing Sunlands and all the Beijing Sunlands Subsidiaries. Tianjin Sunlands, Tianjin Shangde and its subisidiaries, and the shareholders of Tianjin Shangde have entered into a Business Operation Agreement on May 21, 2018, the terms of which are substantially the same as the agreement of Beijing Sunlands summarized above. 1. ORGANIZATION AND BASIS OF PRESENTATION - continued The VIE arrangements – continued • Agreements that transfer economic benefits to the Company – continued Equity Interest Pledge Agreement Pursuant to the equity interest pledge agreement among Wuhan Zhibo, the shareholders of Beijing Sunlands and its subsidiaries, the shareholders of Beijing Sunlands pledged all of their equity interests in Beijing Sunlands to Wuhan Zhibo as security for performance of the obligations of Beijing Sunlands and its shareholders under the exclusive technical consultation and service agreements, the option agreement and the business operation agreement. The shareholders of Beijing Sunlands shall instruct Beijing Sunlands not to distribute any dividends and shall not approve any profit distribution plan. If any of the specified events of default occurs, Wuhan Zhibo may exercise the right to enforce the pledges after giving a notice of default to the shareholders of Beijing Sunlands. Wuhan Zhibo may assign any and all of its rights and obligations under equity interest pledge agreement to its designee(s) at any time. The equity interest pledge agreement is binding on the shareholders of Beijing Sunlands and their successors and shall be valid with respect to the shareholders of Beijing Sunlands and each of its successors. Tianjin Sunlands and the shareholders of Tianjin Shangde and its subisidiaries have entered into an Equity Interest Pledge Agreement on May 21, 2018, the terms of which are substantially the same as the agreement of Wuhan Zhibo summarized above. • Agreements that provide the Company effective control over Beijing Sunlands and Tianjin Shangde Option Agreement Pursuant to the option agreement among Wuhan Zhibo, the shareholders of Beijing Sunlands and Beijing Sunlands, each of the shareholders irrevocably granted Wuhan Zhibo a right to purchase or designate a third party to purchase, equity interests in Beijing Sunlands then held by each shareholder at once or at multiple times at any time in part or in whole at Wuhan Zhibo’s sole and absolute discretion to the extent permitted by PRC law. The shareholders of Beijing Sunlands shall promptly surrender all considerations they received from the exercise of the options to Wuhan Zhibo or the designated third party free of charge. Without Wuhan Zhibo’s prior written consent, the shareholders of Beijing Sunlands shall not, individually or collectively, make or procure Beijing Sunlands to make any transaction or conduct that has a material adverse effect on the assets, liabilities, operations, equity and other legal rights of Beijing Sunlands. Without Wuhan Zhibo’s prior written consent, Beijing Sunlands shall not enter into any contract exceeding RMB50, except the contracts in the ordinary course of the business. Beijing Sunlands shall not be dissolved or liquidated without prior written consent by Wuhan Zhibo. The shareholders of Beijing Sunlands waive their rights of pre-emption in regard to the transfer of equity interest by any other shareholder of Beijing Sunlands to Wuhan Zhibo as instructed. Tianjin Sunlands, the shareholders of Tianjin Shangde and Tianjin Shangde have entered into an Option Agreement on May 21, 2018, the terms of which are substantially the same as the agreement of Wuhan Zhibo summarized above. Powers of Attorney Pursuant to the powers of attorney executed by the shareholders of Beijing Sunlands, the shareholders of Beijing Sunlands each irrevocably authorized Wuhan Zhibo to act on their respective behalf as exclusive agent and attorney with respect to all rights of shareholders concerning all equity interests held by each of them in Beijing Sunlands, including but not limited to propose to convene shareholder meetings, accept any notice with respect to the convening and proceeding of the shareholder meeting, attend shareholder meetings, sign the shareholders resolutions on behalf of, exercise all the shareholder’s rights and Beijing Sunlands’ articles of association (including but not limited to voting rights and the sale, transfer, pledge, or dispose of all equity interests held in part or in whole), and designate and appoint on their respective behalf the president, directors, supervisors, CEO, chief financial officer and other senior management members of Beijing Sunlands. 1. ORGANIZATION AND BASIS OF PRESENTATION - continued The VIE arrangements – continued • Agreements that provide the Company effective control over Beijing Sunlands and Tianjin Shangde – continued Powers of Attorney – continued The shareholders of Tianjin Shangde each irrevocably authorized Tianjin Sunlands to act on their respective behalf as executive agent and attorney with respect to all rights of shareholders pursuant the power of attorney executed on May 21, 2018. Spousal Consent Letters Pursuant to the spousal consent letters executed by the spouses of the general partners of entities as the shareholders of Beijing Sunlands and Tianjin Shangde, the signing spouse confirmed and agreed that the equity interests of Beijing Sunlands and Tianjin Shangde are the own property of their spouses and shall not constitute the jointly possessed property of the couples. The spouses also irrevocably waived any potential right or interest that may be granted by operation of applicable law in connection with the equity interests of Beijing Sunlands and Tianjin Shangde held by their spouse s. As a result of the contractual arrangements above, Wuhan Zhibo and Tianjin Sunlands bear the economic risks and receive the economic benefits of the VIEs and are the primary beneficiary of the VIEs. Therefore, the Company has consolidated the financial results of the VIEs and their subsidiaries in its consolidated financial statement s. Risks in relation to VIE structure The Company believes that the contractual arrangements with Beijing Sunlands, Tianjin Shangde and their shareholders are in compliance with existing PRC laws and regulations and are legally enforceable. However, the contractual arrangements are subject to risks and uncertainties, including : • Beijing Sunlands, Tianjin Shangde and their shareholders may have or develop interests that conflict with the Group’s interests, which may lead them to pursue opportunities in violation of the aforementioned contractual agreements. If the Group cannot resolve any conflicts of interest or disputes between the Group and the shareholders of Beijing Sunlands and Tianjin Shangde, the Group would have to rely on legal proceedings, which could result in disruption of its business, and there is substantial uncertainty as to the outcome of any such legal proceedings . • Beijing Sunlands, Tianjin Shangde and their shareholders could fail to obtain the proper operating licenses or fail to comply with other regulatory requirements. As a result, the PRC government could impose fines, new requirements or other penalties on the VIEs or the Group, mandate a change in ownership structure or operations for the VIEs or the Group, restrict the VIEs or the Group’s use of financing sources or otherwise restrict the VIEs or the Group’s ability to conduct business . • The PRC government may declare the aforementioned contractual arrangements invalid. They may modify the relevant regulations, have a different interpretation of such regulations, or otherwise determine that the Group or the VIEs have failed to comply with the legal obligations required to effectuate such contractual arrangements. • If the legal structure and contractual arrangements were found to be in violation of PRC laws and regulations, the PRC government may restrict or prohibit the Group’s business and operations in China. The Group’s ability to conduct its business may be negatively affected if the PRC government were to carry out any of the aforementioned actions. As a result, the Group may not be able to consolidate Beijing Sunlands, Tianjin Shangde and their subsidiaries in the consolidated financial statements as the Group may lose the ability to exert effective control over Beijing Sunlands, Tianjin Shangde and their shareholders, and the Group may lose the ability to receive economic benefits from Beijing Sunlands and Tianjin Shangde . 1. ORGANIZATION AND BASIS OF PRESENTATION - continued The VIE arrangements - continued The following financial information of the VIEs and their subsidiaries as of December 31, 2017 and 2018 and for each of the three years in the period ended December 31, 2018 was included in the accompanying consolidated financial statements after elimination of intercompany transactions and balances within the subsidiaries, VIEs and their subsidiaries: As of December 31, 2017 2018 RMB RMB Cash and cash equivalents 101,680 80,371 Short-term investments 309,070 587,051 Prepaid expenses and other current assets 38,813 46,601 Total current assets 507,410 818,480 Total assets 954,006 1,196,336 Accrued expenses and other current liabilities 223,298 241,204 Deferred revenue, current 1,325,954 1,765,085 Payables to acquire buildings 180,390 — Total current liabilities 1,729,642 2,006,289 Deferred revenue, non-current 784,474 1,520,940 Other non-current liabilities — 135 Total liabilities 2,514,116 3,527,364 For the years ended December 31, 2016 2017 2018 RMB RMB RMB Net revenues 418,910 970,162 1,973,985 Net (loss)/income (253,563 ) (606,946 ) 393,063 Net cash generated from operating activities 89,272 845,616 1,448,005 Net cash used in investing activities (117,695 ) (375,802 ) (315,198 ) Net cash generated from (used in) financing activities 47,080 (391,237 ) 8,018 There are no consolidated VIEs’ assets that are collateral for the VIEs’ obligations and which can only be used to settle the VIEs’ obligations.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Significant Accounting Policies	2. SIGNIFICANT ACCOUNTING POLICIES Basis of presentation and use of estimates The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosures of contingent assets and liabilities at the balance sheet dates and the reported amounts of revenues and expenses during the reporting periods. Significant estimates and assumptions reflected in the Group’s financial statements include, but are not limited to, consolidation of VIEs, valuation allowance for deferred tax assets, the variable consideration to be earned under refundable course model, useful lives of property and equipment, impairment of long-term assets and valuation of share-based compensation. Actual results could materially differ from those estimates. Principles of consolidation The consolidated financial statements include the financial statements of the Company and its subsidiaries, and VIEs and VIEs’ subsidiaries. All intercompany transactions and balances were eliminated upon consolidation. 2. SIGNIFICANT ACCOUNTING POLICIES - continued Foreign currency translation and transactions The Group’s reporting currency is Renminbi (“RMB”). The functional currency of the subsidiaries incorporated outside the mainland China is United States dollar (“US dollar” or “US$”). The functional currency of all the other subsidiaries and the VIEs and VIEs’ subsidiaries is RMB. Monetary assets and liabilities denominated in currencies other than the applicable functional currencies are translated into the functional currencies at the prevailing rates of exchange at the balance sheet date. Nonmonetary assets and liabilities are remeasured into the applicable functional currencies at historical exchange rates. Revenues and expenses are translated using the average rate of exchange in effect during the reporting period. Translation adjustments are reported and shown as a separate component of other comprehensive loss in the consolidated statements of changes in shareholders’ deficit and the consolidated statements of comprehensive loss. Transactions in currencies other than the functional currencies during the year are converted into the applicable functional currencies at the applicable rates of exchange prevailing at the dates of the transactions. Transaction gains and losses are recorded in the consolidated statements of operations. Convenience Translation The Group’s business is primarily conducted in China and all of the revenues are denominated in RMB. However, periodic reports made to shareholders will include current period amounts translated into US dollars using the then current exchange rates, for the convenience of the readers. Translations of balances in the consolidated balance sheets, and the related consolidated statements of operations, shareholders’ deficit and cash flows from RMB into US dollars as of and for the year ended December 31, 2018 are solely for the convenience of the readers and were calculated at the rate of US$1.00= RMB6 Cash and cash equivalents Cash and cash equivalents comprise cash at banks and on hand and term deposits, which have original maturities of three months or less when purchased and are subject to an insignificant risk of changes in value. The carrying value of cash equivalents approximates market value. Short-term investments Short-term investments consist of financial products with unsecured principal purchased from commercial banks and financial institutions which have original maturities of less than one year. The carrying amount of these short-term investments approximates their fair values due to the short-term maturities of these investments and are carried at cost. The Group reviews its short-term investments for impairment whenever an event or circumstance indicates that impairment has occurred. The Group considers available quantitative and qualitative evidence in evaluating the potential impairment of its short-term investments. An impairment charge is recorded in the consolidated statements of operations if the carrying amount of an investment exceeds the investment’s fair value . Long-term investments Investee companies over which the Group has the ability to exercise significant influence, but does not have a controlling interest through investment in common shares or in-substance common shares, are accounted for using the equity method. Significant influence is generally considered to exist when the Group has an ownership interest in the voting stock of the investee between 20% and 50%, and other factors, such as representation on the investee’s board of directors, voting rights and the impact of commercial arrangements, are also considered in determining whether the equity method of accounting is appropriate. For certain investments in limited partnerships, where the Group holds less than a 20% equity or voting interest, the Group may also have significant influence. 2. SIGNIFICANT ACCOUNTING POLICIES - continued Long-term investments - continued Under the equity method of accounting, the Group initially records its investment at cost and subsequently recognizes the Group’s proportionate share of each equity investee’s net income or loss after the date of investment into earnings and adjusts the investment carrying amount accordingly. The Group reviews its equity method investments for impairment whenever an event or circumstance indicates that any other-than-temporary impairment has occurred. The Group considers available quantitative and qualitative evidence in evaluating potential impairment of its equity method investments. An impairment charge is recorded when the carrying amount of the investment exceeds its fair value and this condition is determined to be other-than-temporary. Fair value Fair value is the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value measurements for assets and liabilities required or permitted to be recorded at fair value, the Group considers the principal or most advantageous market in which it would transact and it considers assumptions that market participants would use when pricing the asset or liability. Authoritative literature provides a fair value hierarchy which prioritizes the inputs to valuation techniques used to measure fair value into three broad levels. The level in the hierarchy within which the fair value measurement in its entirety falls is based upon the lowest level of input that is significant to the fair value measurement as follows: Level 1 Level 1 applies to assets or liabilities for which there are quoted prices in active markets for identical assets or liabilities. Level 2 Level 2 applies to assets or liabilities for which there are inputs other than quoted prices included within Level 1 that are observable for the asset or liability such as quoted prices for similar assets or liabilities in active markets; quoted prices for identical assets or liabilities in markets with insufficient volume or infrequent transactions (less active markets); or model-derived valuations in which significant inputs are observable or can be derived principally from, or corroborated by, observable market data. Level 3 Level 3 applies to assets or liabilities for which there are unobservable inputs to the valuation methodology that are significant to the measurement of the fair value of the assets or liabilities. Financial instruments The Group’s financial instruments consist primarily of cash and cash equivalents, short-term investments, amounts due from related parties, other current liabilities and long-term debt. The carrying amount of long-term debt approximates fair value as its interest rates are at the same level of current market yield for comparable debts. The carrying amounts of other financial instruments approximate their fair values due to short-term maturities . Property and equipment, net Property and equipment are stated at cost and are depreciated using the straight-line method over the estimated useful lives of the assets, as follows: Category Estimated useful life Buildings 36-37 years Leasehold and buildings improvements Shorter of lease term or expected useful life Electronic and office equipment 3-5 years 2. SIGNIFICANT ACCOUNTING POLICIES - continued Property and equipment, net - continued Repair and maintenance costs are charged to expense as incurred, whereas the cost of renewals and betterment that extends the useful lives of property and equipment are capitalized as additions to the related assets. Retirements, sales and disposals of assets are recorded by removing the cost and accumulated depreciation from the asset and accumulated depreciation accounts with any resulting gain or loss reflected in the consolidated statements of operations. Intangible assets, net Intangible assets are amortized using the straight-line basis over the estimated useful lives as follows: Category Estimated useful life Computer software 3 years Impairment of long-lived assets The Group reviews its long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may no longer be recoverable. When these events occur, the Group measures impairment by comparing the carrying value of the long-lived assets to the estimated undiscounted future cash flows expected to result from the use of the assets and their eventual disposition. If the sum of the expected undiscounted cash flow is less than the carrying amount of the assets, the Group would recognize an impairment loss based on the fair value of the assets. The Group did not record any impairment losses on its long-lived assets during the years ended December 31, 2016, 2017 and 2018. Revenue recognition In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, “Revenue from Contracts with Customers (Topic 606).” This standard replaced existing revenue recognition rules with a comprehensive revenue measurement and recognition standard and expanded disclosure requirements. The ASU also includes guidance regarding the accounting for contract acquisition costs, which includes sales commissions. The Group has early adopted the new standard as of January 1, 2017 using the full retrospective method which requires the Group to present its financial statements for all periods as if Topic 606 had been applied to all prior periods. The Group did not apply practical expedients as provided under Topic 606. The Group follows five steps for its revenue recognition under Topic 606: (i) identify the contract(s) with a customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations in the contract, and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Group’s revenue is reported net of discount, business tax, value added tax and related surcharges. The primary sources of the Group’s revenues are as follows: Online education services For online education services, the Group provides an integrated online education service package to students, including online live streaming audio-video interactive course content, recorded previous live audio-video course content, quiz banks, online chat rooms, and educational contents. The services and goods provided in the package are highly interdependent and interrelated in the context of the contract and are only considered accessory services to the online live streaming and recorded courses which are not distinct and are not sold standalone. Therefore, the Group’s integrated online education services package is accounted for as a single performance obligation. The weighted average service period for degree- or diploma-oriented post-secondary courses and professional certification preparation and professional skills courses was 31 months and 20 months, respectively, for the year ended December 31, 2018. The transaction price of the integrated online education service package is determined by the contract amount net of any discounts. Students are offered a full, unconditional refund within 24 hours upon enrollment, and a partial refund for the undelivered courses, excluding registration fees, within 7 days . 2. SIGNIFICANT ACCOUNTING POLICIES - continued Revenue recognition – continued Online education services – continued Online education services consist of two types of revenue models—the non-refundable course model and the refundable course model. Revenues for the non-refundable course model are recognized on a straight line basis over the service period from the registration day to the day on which the service period ends. For the refundable course model, the Group provides a student the ability to apply for a refund if the student achieves certain agreed conditions. The Group estimates the variable consideration to be earned to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is resolved and recognizes revenue over time from the registration day to the day on which the service period ends on a straight line basis. The Group’s estimates of variable consideration and determination of whether to include estimated amounts in the transaction price are based largely on an assessment of the Group’s anticipated performance and all information (historical, current and forecasted) that is reasonably available. Under the non-refundable course model, for certain online courses, the service period includes a regular period plus an extended period. The Group offers students an extended period after the regular period if conditions are met. Online education services with insurance coverage since 2018 Under the non-refundable course model, for certain online courses, the Group offers a bundle service including an integrated online education service package with insurance coverage for tuition refund. If the refundable conditions are met, students could claim the insurance equal to full or partial amount of the service fee. The Group identifies that the integrated online education service package and the insurance service are two separate performance obligations as students benefit from each service on its own and they are separately identifiable in the contract. The Group records revenue generated from online education services with insurance coverage on a gross basis as the Group is acting as the principal to fulfill all obligation and control all the services transferred to the students. The Group estimates the stand-alone selling prices of each performance obligation based on the expected cost of satisfying each performance obligation plus an estimated margin for each performance obligation. Revenues for integrated online education service and the insurance coverage service are recognized based on their relative stand-alone selling price over their respective service periods on a straight line basis from the registration day to the day on which the service period ends as the students simultaneously receives and consumes the benefits provided by these two performance obligations. The Group’s deferred costs represent the unamortized incremental sales commission relating to obtaining of customers contract, and the contract liability primarily consists of deferred revenue. Student Financing The Group offers an installment payment option to students, under which the students obtain loans, from accredited credit sources (“Loan Companies”) for the purpose of satisfying the student’s tuition payment due. The borrowing student is obligated to repay the loan principal in installments over periods ranging from 3 months to 12 months to the Loan Companies, while the Group agrees with the Loan Companies to bear the student’s interest expense and service fees. The Loan Companies remit the tuition to the Group for students to complete the registration. The interest expense and service fees are recorded as a reduction of the transaction price. Commission revenue The Group earns commission revenue by providing referral services to third party education institutions. Commission revenue is recognized when the referred students registered at the third party education institutions and the tuition fees are paid, by when the performance obligation is satisfied. 2. SIGNIFICANT ACCOUNTING POLICIES - continued Deferred Revenue Revenues related to the Group’s online courses are recognized over time. Deferred revenue consists of tuition fees received from students for which services have not yet been provided to students. Business taxes Prior to May 2016, Beijing Sunlands and its subsidiaries were subject to business tax and related surcharges at a rate of 3.36% on revenues related to educational services and 5.6% on non-educational services, respectively. The net revenues are presented net of those taxes incurred. Value added taxes (“VAT”) Beginning in May 2016, in accordance with Tax rule (Cai Shui [2016] No. 68), the non-academic educational programs and services are subject to a simple VAT collection method at a rate of 3%. Entities which are subject to the tax rate of 3% are not allowed to offset qualified input VAT paid to suppliers against their output VAT liabilities. The Group’s educational services, which were previously subject to business tax, are therefore subject to VAT at the rate of 3%. For Tianjin Shangde, the educational services are subject to VAT at the rate of 6%. For non-educational services, the VAT rate is 6%, in accordance with Tax rule (Cai Shui [2016] No. 36). Cost of revenue Cost of revenues consist of expenditures incurred in the generation of the Group’s revenue, includes but not limited to salaries and benefits paid to teachers, related rental expenses, server management costs, bandwidth costs, payment processing costs, insurance cost, depreciations for property and equipment and amortizations for intangible assets. Product development expenses Product development expenses primarily consist of (i) salaries and benefits for innovation and development of course content, product and technology development personnel, and (ii) office rental, general expenses and depreciation and amortization expenses associated with the product development activities. The Group’s product development activities primarily consist of the development and enhancement of the Group’s educational content, applications and platforms. The Group has expensed all product development expenses when incurred. Sales commission The incremental sales commission relating to obtaining of the customer contract and expected to be recovered is accounted for as an incremental cost of obtaining a contract pursuant to ASC340-40 and is capitalized as deferred costs when incurred. The capitalized cost is amortized in the same manner as the revenue recognized and is included in “sales and marketing expenses” in the consolidated statements of operations. Other sales commission incurred regardless of whether the contract was obtained is recognized as an expense when incurred. 2. SIGNIFICANT ACCOUNTING POLICIES - continued Advertising expenditure Advertising expenditure, mainly includes search engine marketing and mobile marketing expenses, is expensed when incurred and is included in sales and marketing expenses in the consolidated statements of operations. Advertising expenses were RMB188,516, RMB499,294 and RMB983,012 for the years ended December 31, 2016, 2017 and 2018, respectively. Sales and marketing expenses Sales and marketing expenses primarily consist of (i) salaries and benefits for sales and marketing personnel, (ii) search engine marketing and mobile marketing expenses and other advertising expenses, (iii) office rental, general expenses and depreciation and amortization expenses associated with the sales and marketing activities. Operating leases Leases where substantially all the rewards and risk of assets remain with the leasing company are accounted for as operating leases. Payments made under operating leases are charged to the consolidated statements of operations on a straight-line basis over the lease term. Government subsidies For the government subsidies not subject to further performance obligations or future returns, the Group records the amounts as other income when received from local government authority. Whereas for the government subsidies with future performance obligations, the Group recognizes those as liabilities when received until the performances obligations have been met at which time, those are recognized as other income. Government subsidies received and recorded as other income amounted to RMB1,601, RMB3,223 and RMB28,688 for the years ended December 31, 2016, 2017 and 2018, respectively. Income taxes Current income taxes are provided for in accordance with the laws of the relevant tax authorities. Deferred income taxes are recognized when temporary differences exist between the tax bases of assets and liabilities and their reported amounts in the financial statements. Net operating loss carry forwards and credits are applied using enacted statutory tax rates applicable to future years. Deferred tax assets are reduced by a valuation allowance when, in the opinion of management, it is more-likely-than-not that a portion of or all of the deferred tax assets will not be realized. The impact of an uncertain income tax position is recognized at the largest amount that is more-likely-than-not to be sustained upon audit by the relevant tax authority. An uncertain income tax position will not be recognized if it has less than a 50% likelihood of being sustained. Interest and penalties on income taxes will be classified as a component of the provisions for income taxes. Comprehensive loss Comprehensive loss includes net loss and foreign currency translation adjustments and is reported in the consolidated statements of comprehensive loss. The Group presents the components of net loss, the components of other comprehensive loss and total comprehensive loss in two separate but consecutive statements. 2. SIGNIFICANT ACCOUNTING POLICIES - continued Net loss per share Prior to IPO, basic net loss per share is computed by dividing net loss attributable to ordinary shareholders of the Company by the weighted average number of ordinary shares outstanding during the year using the two-class method. The holders of the convertible redeemable preferred shares are entitled to share dividends on a pro rata basis, as if their shares had been converted into ordinary shares. Accordingly, the Company has used the two-class method in computing net loss per share. Under the two-class method, net loss is allocated on a pro rata basis to each class of ordinary shares and other participating securities based on their participating rights. After IPO, basic net loss per share is computed by dividing net loss attributable to ordinary shareholders of the Company by the weighted average number of common shares outstanding during the year. Diluted net loss per share reflects the potential dilution that could occur if securities or other contracts to issue common shares were exercised into common shares. To calculate the number of shares for diluted loss per share, the effect of the share options is computed using the treasury stock method. As the Company was loss making for the years ended December 31, 2016, 2017 and 2018, the effect of potential issuances of shares for the convertible redeemable preferred shares and share options would be anti-dilutive, and therefore basic and diluted losses per share are the same in those periods. Share-based compensation Share-based compensation with employees is measured based on the grant date fair value of the equity instrument. Share-based compensation expenses, net of forfeitures, are recognized over the requisite service period based on a straight-line basis with a corresponding impact reflected in additional paid-in capital. Share-based compensation awards which require the issuance of a variable number of shares to settle a fixed monetary amount are recorded as liabilities. Significant risks and uncertainties Foreign currency risk RMB is not a freely convertible currency. The State Administration for Foreign Exchange, under the authority of the People’s Bank of China, controls the conversion of RMB into foreign currencies. The value of RMB is subject to changes in central government policies and to international economic and political developments affecting supply and demand in the China Foreign Exchange Trading System market. The cash and cash equivalents of the Group included aggregate amounts of RMB104,244 and RMB157,103, which were denominated in RMB at December 31, 2017 and 2018, representing 18.6% and 12.6% of the cash and cash equivalents at December 31, 2017 and 2018, respectively. Concentration of credit risk Financial instrument that potentially expose the Group to significant concentration of credit risk primarily consist of cash and cash equivalents, short-term investments, amounts due from related parties and prepaid expenses and other current assets. The Group places its cash and cash equivalents and short-term investments in financial institutions with high credit ratings. There are no revenues from customers which individually represent greater than 10% of the total net revenues for any year of the three years period ended December 31, 2018. Newly adopted accounting pronouncements In January 2016, the FASB issued a new pronouncement ASU 2016-01 Financial Instruments-Overall: Recognition and Measurement of Financial Assets and Financial Liabilities. The ASU requires equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income. The ASU also requires an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. 2. SIGNIFICANT ACCOUNTING POLICIES - continued Newly adopted accounting pronouncements - continued ASU 2016-01 was further amended in February 2018 by ASU 2018-03, "Technical Corrections and Improvements to Financial Instruments—Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities". This update was issued to clarify certain narrow aspects of guidance concerning the recognition of financial assets and liabilities established in ASU 2016-01. This includes an amendment to clarify that an entity measuring an equity security using the measurement alternative may change its measurement approach to a fair valuation method in accordance with Topic 820, Fair Value Measurement, through an irrevocable election that would apply to that security and all identical or similar investments of the same issued. ASU 2016-01 and ASU 2018-03 are effective for public companies for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Adoption of the amendment must be applied by means of a cumulative-effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption, except for amendments related to equity instruments that do not have readily determinable fair values which should be applied prospectively. The Group has adopted the new standard as of January 1, 2018, which did not result in a material impact on its consolidated financial statements. Recent accounting pronouncements not yet adopted In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). The guidance supersedes existing guidance on accounting for leases with the main difference being that operating leases are to be recorded in the statement of financial position as right-of-use assets and lease liabilities, initially measured at the present value of the lease payments. For operating leases with a term of 12 months or less, a lessee is permitted to make an accounting policy election not to recognize lease assets and liabilities. For public business entities, the guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early application of the guidance is permitted. In July 2018, the FASB issued ASU 2018-10, Codification Improvements to Topic 842, Leases. The amendments in this ASU are of a similar nature to the items typically addressed in the Codification improvements project. However, the Board decided to issue a separate ASU for the improvements related to Accounting Standards Update No. 2016-02, Leases (Topic 842), to increase stakeholders’ awareness of the amendments and to expedite the improvements. The amendments in this ASU affect narrow aspects of the guidance issued in ASU 2016-02. For entities that have early adopted Topic 842, the amendments in this Update should be effective upon issuance of the final Update and the transition requirements should be the same as those in Topic 842. For entities that have not adopted Topic 842, the effective date and transition requirements of the amendments should be the same as the effective date and transition requirements in Topic 842. In July 2018, the FASB issued ASU 2018-11, Leases (Topic 842): Targeted Improvements. The amendments in this ASU related to separating components of a contract affect the amendments in ASU 2016-02, which are not yet effective but can be early adopted. For entities that have not adopted Topic 842 before the issuance of this ASU, the effective date and transition requirements for the amendments in this ASU related to separating components of a contract are the same as the effective date and transition requirements in ASU 2016-02. All entities, including early adopters that elect the practical expedient related to separating components of a contract in this ASU must apply the expedient, by class of underlying asset, to all existing lease transactions that qualify for the expedient at the date elected. Specifically, under the amendments in ASU 2018-11, (1) entities may elect not to recast the comparative periods presented when transitioning to ASC 842 and (2) lessors may elect not to separate lease and nonlease components when certain conditions are met. Before ASU 2018-11 was issued, transition to the new lease standard required application of the new guidance at the beginning of the earliest comparative period presented in the financial statements. The Group has substantially completed its evaluation of the effect of the adoption of this ASU and expects the adoption will result in an increase in the assets and liabilities on the consolidated balance sheet for the operating leases and will have insignificant impact on its consolidated statements of operations and cash flows. 2. SIGNIFICANT ACCOUNTING POLICIES - continued Recent accounting pronouncements not yet adopted - continued In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820)—Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement. The amendments in this ASU improve the effectiveness of fair value measurement disclosures and modify the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement, based on the concepts in FASB Concepts Statement, Conceptual Framework for Financial Reporting—Chapter 8: Notes to Financial Statements, including the consideration of costs and benefits. The amendments in this ASU are effective for all entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. Early adoption is permitted. T

Short-Term Investments

Short-Term Investments	12 Months Ended
	Dec. 31, 2018
Investments Debt And Equity Securities [Abstract]
Short-Term Investments	3 . SHORT-TERM INVESTMENTS Short-term investments consist of various financial products with unsecured principal from financial institutions in China at original maturity less than one year when purchased. While these financial products are not publicly traded, the Group estimated that their fair value approximated the costs considering their short-term maturities and high credit quality. As of December 31, 2017 2018 RMB RMB Short-term investments 353,070 1,028,564 No impairment loss was recognized for the three years ended December 31, 2016, 2017 and 2018.

Prepaid Expenses and Other Curr

Prepaid Expenses and Other Current Assets	12 Months Ended
	Dec. 31, 2018
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Prepaid Expenses and Other Current Assets	4 . PREPAID EXPENSES AND OTHER CURRENT ASSETS Prepaid expenses and other current assets consisted of the following: As of December 31, 2017 2018 RMB RMB Prepaid and input VAT 14,440 58,234 Prepaid marketing expenses 9,059 23,756 Interest receivables (1) — 11,632 Prepaid expenses (2) 10,081 10,820 Deferred IPO expenses 5,746 — Deposits (3) 5,154 4,595 Receivables from third-party payment platforms 3,045 3,886 Staff advances 932 9,242 Others 536 2,743 Total 48,993 124,908 (1) Represented interest receivables from short-term investments (Note 3). ( 2 ) Represented the prepaid expenses for telecommunications, network, service for online live steaming, advertising and rental. ( 3 ) Represented rental deposits, deposits for search engine marketing activities and deposits for leasehold improvement of buildings which all being refundable within one year.

Deferred Costs

Deferred Costs	12 Months Ended
	Dec. 31, 2018
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Deferred Costs	5 . DEFERRED COSTS Deferred costs primarily consist of the incremental sales commission and service fee relating to obtaining of customers contract which is expected to be recovered and is capitalized pursuant to ASC340-40. The capitalized sales commission is amortized in the same manner the related revenue being recognized. The movements of deferred costs for the years ended December 31, 2017 and 2018 are as follows: As of December 31, 2017 2018 RMB RMB Beginning balances (current and non-current) 25,228 98,260 Additions 121,327 374,594 Amortizations (48,213 ) (145,488 ) Impairments (82 ) (99 ) Ending balances (current and non-current) 98,260 327,267 Deferred costs, current 55,073 180,657 Deferred costs, non-current 43,187 146,610

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Property and Equipment, Net	6 . PROPERTY AND EQUIPMENT, NET Property and equipment consisted of the following: As of December 31, 2017 2018 RMB RMB Leasehold and buildings improvements 40,675 91,265 Electronic and office equipment 16,061 29,936 Buildings (1) 485,588 480,271 Total cost 542,324 601,472 Less: Accumulated depreciation (17,036 ) (41,961 ) Property and equipment, net 525,288 559,511 (1) In 2017, the Group purchased two buildings in Wuhan (Building A and B) and one building in Guangzhou (Building C) with a total consideration of RMB480,271. RMB60,000 of the consideration was paid by a mortgage loan provided by a PRC bank in August 2018 (Note 12). Depreciation expenses were RMB4,993, RMB7,333 and RMB24,930 for the years ended December 31, 2016, 2017 and 2018, respectively.

Intangible Assets, Net

Intangible Assets, Net	12 Months Ended
	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible Assets, Net	7 . INTANGIBLE ASSETS, NET The balance of intangible assets consisted of the following: As of December 31, 2017 2018 RMB RMB Computer software 3,092 3,757 Less: Accumulated amortization (1,540 ) (2,388 ) Intangible assets, net 1,552 1,369 Amortization expenses were RMB477, RMB776 and RMB 848 The intangible assets amortization expenses for each of the following fiscal years are as follows: Amortization RMB 2019 717 2020 553 2021 99 Total 1,369

Long-Term Investments

Long-Term Investments	12 Months Ended
	Dec. 31, 2018
Equity Method Investments And Joint Ventures [Abstract]
Long-Term Investments	8 . LONG-TERM INVESTMENTS Long-term investments consisted of the following: As of December 31, 2017 2018 RMB RMB Partnership A (1) 3,300 3,911 Partnership B (2) — 26,098 Total 3,300 30,009 (1) In January 2017, the Group made an investment of RMB8,190 to a limited partnership A (the “Partnership A”) in the PRC, representing 90% of the total investment amount of Partnership A. The Group is the limited partner with no substantive kickout rights, nor substantive participating rights. (2) In August 2018, the Group made an investment of RMB25,000 to a limited partnership B (the “Partnership B”) in the PRC, representing 3.3% of total investment amount of Partnership B. The Group committed to invest another RMB25,000 to this investee upon the request of the general partner of the Partnership B (Note 20). The Group used equity method of accounting to record these investments since the Group has the ability to exercise significant influence but does not have control over the investees. The Group reviewed the investments for impairment whenever an event or circumstance indicates that an other-than-temporary impairment has occurred. As of December 31, 2017 and 2018, no impairment loss was recorded in regard to these investments.

Other Non-Current Assets

Other Non-Current Assets	12 Months Ended
	Dec. 31, 2018
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Other Non-Current Assets	9 . OTHER NON-CURRENT ASSETS Other non-current assets consisted of the following: As of December 31, 2017 2018 RMB RMB Rental deposits (1) 9,689 12,772 Prepayment to acquire a building (2) 119,952 404,725 Others — 1,203 Total 129,641 418,700 (1) Rental deposits represent office and enrollment centers’ rental deposits for the Group’s daily operations, which are not refundable within one year. (2) The amounts represent the prepayment for one building (Building D) in Wuhan and the building was under construction by the real estate developer as of December 31, 2018.

Accrued Expenses And Other Liab

Accrued Expenses And Other Liabilities	12 Months Ended
	Dec. 31, 2018
Payables And Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	10 . ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES The components of accrued expenses and other liabilities are as follows: As of December 31, 2017 2018 RMB RMB Salary and welfare payables 148,337 124,137 Accrued marketing expenses 16,133 120,269 Accrued rental expenses 33,693 51,087 Accrued service fees (1) 13,595 94,789 Other tax liabilities 9,915 29,872 Advanced deposits (2) 6,081 6,650 Refund liability (3) 2,452 6,625 Payables for leasehold improvement and intangible assets 2,180 4,911 American Depositary Receipt commission - within one year — 3,482 Payables to educational institutions (4) — 6,024 Payables for share repurchase — 857 Other payables 3,514 6,581 235,900 455,284 (1) The balance represented accrued expenses for outsourced service providers and other professional services. (2 ) Advanced deposits consisted of (1) down payments paid by prospective students before contract signing and (2) insurance (3 ) Refund liability amounted to RMB2,452 and RMB6,625 as of December 31, 2017 and 2018, respectively, representing the estimated amounts of deferred revenue with contingency in cash refund. (4 ) The balances represented tuition fees collected from the students for their registrations with educational institutions.

Revenues and Deferred Revenue

Revenues and Deferred Revenue	12 Months Ended
	Dec. 31, 2018
Disaggregation Of Revenue [Abstract]
Revenues and Deferred Revenue	11 . REVENUES AND DEFERRED REVENUE For the years ended December 31, 2016, 2017 and 2018, all of the Group’s revenues were generated in the PRC, and the disaggregated revenues by types and models were as follows: For the years ended December 31, 2016 2017 2018 RMB RMB RMB Disaggregation of revenues Revenue by types: Gross revenues: Degree- or diploma-oriented post-secondary courses 296,269 822,832 1,814,178 Professional certification preparation and professional skills courses 122,005 145,840 161,366 Subtotal Online educational courses 418,274 968,672 1,975,544 Commissions 4,528 4,105 6,374 Others 1,284 1,901 587 Total revenues 424,086 974,678 1,982,505 Less: sales tax and surcharges (5,176 ) (4,516 ) (8,520 ) Total net revenues 418,910 970,162 1,973,985 Revenue by models: Gross revenues: Refundable 79,541 126,277 85,630 Non-refundable 338,733 842,395 1,889,914 Subtotal Online educational courses 418,274 968,672 1,975,544 Commissions 4,528 4,105 6,374 Others 1,284 1,901 587 Total revenues 424,086 974,678 1,982,505 Less: sales tax and surcharges (5,176 ) (4,516 ) (8,520 ) Total net revenues 418,910 970,162 1,973,985 The movements of the deferred revenue for the years ended December 31, 2017 and 2018 were as follows (1) As of December 31, 2017 2018 RMB RMB Beginning balance (current and noncurrent) 727,569 2,110,428 Additions 2,381,755 3,214,400 Deductions (998,896 ) (2,038,803 ) Ending balance (current and noncurrent) 2,110,428 3,286,025 Deferred revenue, current 1,325,954 1,765,085 Deferred revenue, non-current 784,474 1,520,940 (1) Amounts presented are inclusive of VAT (see VAT in Note 2).

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
LONG-TERM DEBT	12. LONG-TERM DEBT On August 29, 2018 and November 21, 2018, the Group entered into two s in

Convertible Redeemable Preferre

Convertible Redeemable Preferred Share	12 Months Ended
	Dec. 31, 2018
Temporary Equity Disclosure [Abstract]
Convertible Redeemable Preferred Share	13. CONVERTIBLE REDEEMABLE PREFERRED SHARE On July 5, 2016, Beijing Sunlands issued 20.27% equity interests with preferential rights (“Series A Equity Interest”) to certain third party shareholders (“Series A Preferred Shareholders”) for a total cash consideration of RMB335,000. In August 2017, as an integrated step of the 2017 Reorganization, the Company (1) redeemed certain Series A Equity Interest from one of the holders of Series A Equity Interest at cash consideration of RMB86,000 and (2) newly issued 954,274 Series A Preferred Shares proportionally to the then existing Series A Preferred Shareholders of Beijing Sunlands to mirror the shareholding structure of Beijing Sunlands to the Company. In November 2017, the Series A Preferred Shareholders withdrew the original investment of RMB242,078 from Beijing Sunlands and the proceeds were reinvested in full to the Company in January 2018. In August 2017, the Company issued 826,389 Series B Preferred Shares to a third party investor (the “Series B Preferred Shareholder”) for a cash consideration of US$90,000 (equivalent to RMB601,605). In September 2017, the Company issued 141,264 Series B+ Preferred Shares to a third party investor (the “Series B+ Preferred Shareholder”) for a cash consideration of US$20,000 (equivalent to RMB131,104). Upon the completion of the Company's IPO in March 2018, Series A, Series B and Series B+ Preferred Shares outstanding then were converted into different classes of ordinary shares on a 1:1 basis. 954,274 Series A convertible redeemable preferred shares were converted into 954,274 Class A ordinary shares; 826,389 Series B convertible redeemable preferred shares were converted into 826,389 Class B ordinary shares; and 141,264 Series B+ convertible redeemable preferred shares were converted into 141,264 Class A ordinary shares. The Series A, Series B and Series B+ Preferred Shares are collectively referred to as the “Preferred Shares”. The key terms of the Preferred Shares are as follows: Conversion Each holder of Preferred Shares have the right to convert any or all of its Preferred Shares into ordinary shares at the quotient of the original issue price divided by the then effective conversion price as defined in the memorandum and articles of association being no less than par value. In addition, all outstanding Preferred Shares shall be automatically converted into ordinary shares upon the consummation of a Qualified IPO. In addition, each Series A Preferred Share shall be automatically converted into ordinary shares upon the consummation of a Series A Target IPO. Qualified IPO was defined as a public offering of the shares on any of the New York Stock Exchange (“NYSE”), the National Association of Securities Dealers Automated Quotations (“NASDAQ”) Global Market or such other stock exchange approved by the Board and in such public offering, (i) the number of Shares newly issued and sold to the public shall represent not less than 10% of the fully diluted share capital of the Company as of immediately following such public offering, and (ii) the per share price to public is not less than the issuance price of Series B+ Preferred Shares, as proportionally adjusted for share splits, share dividends, share combinations and similar events. Series A Target IPO was defined as a public offering of the shares on any of the NYSE, the NASDAQ Global Market or such other stock exchange approved by the Board, and in such public offering, (i) the market capitalization of the Company is not less than US$500,000 immediately following such public offering, and (ii) the aggregate gross proceeds to the Company are not less than US$100,000. Voting Rights The holders of Preferred Shares and the holders of ordinary shares shall vote together based on their shareholding percentages. Dividends The holder of each Preferred Share shall have the right to receive non-cumulative dividends, pari passu with the ordinary shares, on an as-converted basis, when, as and if declared by the Board. 13. CONVERTIBLE REDEEMABLE PREFERRED SHARE - continued Redemption In the event that the Company has not consummated a Series A Target IPO as of the date that is thirty months after August 15, 2017 (or such other later date as approved at any time by the holders of not less than three fourths of the then issued and outstanding Series A Preferred Shares), each Series A Preferred Shareholder shall have the option, but is not required to sell all or a portion of the Series A Preferred Shares held at a price of the original issuance price plus a simple rate of 10% interest per annum since the date of issuance to the date on which the applicable redemption amount is paid in full. The redemption price shall plus all declared but unpaid dividends thereon up to the date of such redemption. The redemption value of the Series A Preferred Shares was RMB303,040 as of December 31, 2017. In the event that the Company has not consummated a Qualified IPO as of the fifth anniversary of August 15, 2017, or has consummated an initial public offering that is not a Qualified IPO at any time prior to the fifth anniversary of August 15, 2017, each Series B Preferred Shareholder shall have the option, but is not required to sell all or a portion of the Series B Preferred Shares held at a price of the original issuance price plus a compound rate of 10% interest per annum since the date of issuance to the date on which the applicable redemption amount is paid in full. The redemption price shall plus all declared but unpaid dividends thereon up to the date of such redemption. The redemption value of the Series B Preferred Shares was RMB623,679 as of December 31, 2017. In the event that the Company has not consummated a Qualified IPO as of the fifth anniversary of September 1, 2017, or has consummated an initial public offering that is not a Qualified IPO at any time prior to the fifth anniversary of September 1, 2017, each Series B+ Preferred Shareholder shall have the option, but is not required to sell all or a portion of the Series B+ Preferred Shares held at a price of the original issuance price plus a compound rate of 10% interest per annum since the date of issuance to the date on which the applicable redemption amount is paid in full. The redemption price shall plus all declared but unpaid dividends thereon up to the date of such redemption. The redemption value of the Series B+ Preferred Shares was RMB135,312 as of December 31, 2017. Liquidation In the event of any liquidation, dissolution, winding up of the Company or any deemed liquidation event (each, a “Liquidation Event”), the proceeds shall be distributed according to the following sequence: (1) first to the Series B and B+ Preferred Shareholders at an amount (the “Series B and B+ Liquidation Preference Amount”) equals the higher of (a) at a 8% compound interest per annum of the original issuance price of Series B and B+ Preferred Shares from the date of issuance to the date of the Liquidation Event, plus any declared but unpaid dividend and (b) an amount equal to such Series B and B+ Preferred Shareholders’ share of proceeds if all the preferred shares were converted into ordinary shares and the proceeds were distributed among the holders of ordinary shares in proportion to the number of ordinary shares held by each such holders; (2) second to Series A Preferred Shareholders at an amount equals the higher of (a) 10% compound interest per annum from the date of issuance to the date of the Liquidation Event, plus any declared but unpaid dividend (“Series A Liquidation Preference Amount”) and (b) two times of the Series A Preferred Shares original issuance price (as proportionally adjusted for share sub-divisions, share dividends, share consolidations, recapitalizations and similar events). (3) third, after the full distribution of Series B Liquidation Preference Amount and the Series A Liquidation Preference Amount, any remaining proceeds shall be distributed among the Series A Preferred Shareholders and the holders of the ordinary shares in proportion to the number of ordinary shares held by each such holder on an as-converted basis.

Ordinary Shares

Ordinary Shares	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Ordinary Shares	14. ORDINARY SHARES On September 18, 2015, the Company authorized 1,000,000,000 shares of a par value of US$0.00005 (equivalent to RMB0.0003) per share and issued 1 ordinary share at par value at incorporation. In August 2017, the Company newly issued 1,909,309 ordinary shares proportionally to the then existing shareholders in relation to the 2017 Reorganization. In October 2017, the shareholders of the Company approved a share split at a 1 to 2 ratio for each ordinary share and Preferred Share. All share and per share amounts for all periods presented herein have been adjusted to reflect the split as if it had occurred at the beginning of the first period presented. In August 2017, subsequent to the 2017 Reorganization, the Company newly issued 146,930 ordinary shares to certain directors and management at no consideration as a share-based compensation (Note 16). In March 2018, the Company completed its IPO and issued 16,478,275 ADSs (representing 659,131 Class A ordinary shares). The net proceeds raised from IPO were RMB1,109,517, Upon the completion of IPO, 4,329,000 ordinary shares outstanding then were designated to 63,714 Class A ordinary shares and 4,265,286 Class C ordinary shares, respectively. On August 29, 2018, the Company’s Board of Directors approved a share repurchase program under which the Company was authorized to repurchase up to US$50,000 of its Class A ordinary shares in the form of ADSs over the following 12 months. 1,127,055 ADSs (equivalent to 45,082 Class A ordinary shares) were repurchased in the year ended December 31, 2018 at a total consideration of RMB34,828. The repurchased shares were presented as treasury stock on the consolidated balance sheet as of December 31, 2018.

Fair Value Measurement

Fair Value Measurement	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurement	15. FAIR VALUE MEASUREMENT Measured or disclosed at fair value on a recurring basis The Group measured its financial assets and liabilities, including cash and cash equivalents, short-term investments, amounts due from related parties and long-term debt on a recurring basis as of December 31, 2017 and 2018. Cash and cash equivalents are classified within Level 1 of the fair value hierarchy because they are valued based on the quoted market price in an active market. The carrying amounts of short-term investments and amounts due from related parties approximate their fair values due to their short-term maturity and are within Level 2 of the fair value hierarchy. The carrying amount of long-term debt approximates fair value as its interest rates are at the same level of current market yield for comparable debts. Measured or disclosed at fair value on a non-recurring basis The Group measures long-term investments at fair value on a nonrecurring basis whenever events or changes in circumstances indicate that the carrying value may no longer be recoverable.

Share Incentive Plan

Share Incentive Plan	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share Incentive Plan	16. SHARE INCENTIVE PLAN 2017 Share Incentive Plan In October 2017, the shareholders of the Company approved the 2017 Share Incentive Plan (the “2017 ESOP”) under which the Company can grant a maximum of 483,846 ordinary shares. On August 24, 2018, the Company further approved an additional 345,503 ordinary shares for issuance, and therefore, 829,349 ordinary shares reserved for issuance under the 2017 ESOP. Scheme I On October 20, 2017, the Company granted 363,452 options under the 2017 ESOP for an exercise price of $0.0047 (equivalent to RMB0.0312). Vesting of Options The options shall vest and become exercisable immediately at the grant date. Exercise of Options The options shall be exercisable before the date of expiration. Expiration of Options Any unexercised option shall be immediately forfeited upon the date of the Company’s IPO. The entire 363,452 options granted under this scheme were exercised at the grant date and a compensation expense of RMB 205,630 was recorded for the year ended December 31, 2017. Scheme II On October 20, 2017, the Company granted 66,053 options under the 2017 ESOP for an exercise price of $84.75 (equivalent to RMB560.95). Vesting of Options The options shall vest and become exercisable in the installments of 10%, 20%, 30% and 40%, respectively on the first, second, third and fourth anniversary of the date of the Company’s IPO. Exercise of Options The options shall be exercisable before the date of expiration. Any unexercised option shall be immediately forfeited upon the tenth anniversary of October 20, 2017. The vesting and exercisability of options granted under Scheme II of the 2017 ESOP are both upon the IPO which is not assessed as probable until the effective date of the IPO. Therefore, no share-based compensation expenses were accrued for the year ended December 31, 2017. Upon the completion of the Company's IPO in March 2018, a compensation expense of RMB2,751 was recorded for the year ended December 31, 2018. 16. SHARE INCENTIVE PLAN - continued Scheme II - continued A summary of option activities and changes during the year ended December 31, 2018 were presented below: Weighted- average Weighted- Weighted- remaining Aggregated average Number of average contractual intrinsic grant date Share option shares exercise price term(years) value fair value RMB RMB RMB Outstanding, December 31, 2017 62,268 560.95 9.81 302 271.90 Forfeited (10,437 ) 560.95 271.90 Outstanding, December 31, 2018 51,831 560.95 8.81 — 271.90 The Company calculated the estimated fair value of the options on the respective grant dates using the binomial option pricing model with the assistance from an independent valuation firm, with the following assumptions used. October 20, Grant Dates 2017 Risk-free interest rate 2.0%-2.4% Volatility 32%-45% Expected dividend yield 0% Exercise multiples 2.2-2.8 Exercise price 0.0312-560.95 Life of option (years) 0.53-10 Fair value of underlying ordinary share 565.80 (1) Risk free rate of interest Risk-free interest rate was estimated based on the yield to maturity of US Sovereign Strips Curve with maturity date closest to the life to expiration, plus country default spread of China as of the valuation dates. (2) Volatility The volatility factor estimated was based on the daily share price volatility of comparable companies for an observation period that matches the life to expiration of share options. (3) Dividend Yield The management does not have any dividend policy after IPO. Hence, the dividend payout ratio is assumed to be 0%. (4) Exercise multiples Exercise multiple is based on empirical research on typical employee stock option exercising behavior. In addition to the Share Incentive Plans disclosed On May 17, 2018, the Company's Board of Directors approved to award awards compensation classified as liabilities which was included in accrued expenses and other current liabilities. 16. SHARE INCENTIVE PLAN - continued Total share-based compensation expense of share-based awards granted to employees, certain directors and management recognized for the years ended December 31, 2016, 2017 and 2018 were as follows: For the years ended December 31, 2016 2017 2018 RMB RMB RMB Cost of revenues — 19,244 314 Sales and marketing expenses — 75,237 773 General and administrative expenses — 194,282 2,764 — 288,763 3,851 As of December 31, 2018, the unrecognized share-based compensation expenses related to share options were RMB14,083, which are expected to be recognized over a weighted average period of 3.2

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	17. INCOME TAXES Cayman Islands Under current law of Cayman Islands, the Company is not subject to income or capital gains taxes. In addition, dividends payments are not subject to tax withholding in the Cayman Islands. Hong Kong The Company’s subsidiary, Sunlands HK is located in Hong Kong and is subject to a two-tiered income tax rate for taxable income earned in Hong Kong with effect from April 1, 2018. The first HK$2 million of profits earned by Sunlands HK will be taxed at 8.25%, while the remaining profits will continue to be taxed at the existing 16.5% tax rate. No provision for Hong Kong profits tax has been made in the consolidated financial statements as it has no assessable income for the years ended December 31, 2016, 2017 and 2018. China The Group’s subsidiaries, VIEs and VIEs’ subsidiaries incorporated in the PRC were generally subject to a corporate income tax rate of 25%. The Enterprise Income Tax Law (the “EIT Law”) of the PRC, effective since January 1, 2008, applies a uniform 25% enterprise income tax rate to all resident enterprises in China, including foreign invested enterprises. From 2015, Previous WFOE qualified as “high and new technology enterprise strongly supported by the State” (“HNTE”) under the EIT Law, and therefore, was entitled to preferential income tax rate of 15% from 2015 through 2017. In 2016, Beijing Sunlands obtained HNTE qualification and was entitled to preferential income tax rate of 15% from 2016 through 2018. The deferred income tax expenses in the consolidated statements of operations were nil, nil and nil for the three years ended December 31, 2018. 17. INCOME TAXES - continued China - continued The reconciliation of the effective tax rate and the statutory income tax rate applicable to PRC operations is as follows: For the years ended December 31, 2016 2017 2018 RMB RMB RMB Loss before income tax expenses (253,567 ) (913,824 ) (928,660 ) Income tax expenses computed at applicable tax rates of 25% (63,392 ) (228,456 ) (232,165 ) Non-deductible and super deduction expenses 2,477 (3,490 ) (8,013 ) Effect of tax holidays and preferential tax rates 24,808 130,296 64,029 Change in valuation allowance 36,107 101,650 176,149 Income tax expenses — — — If the tax holidays granted to Beijing Sunlands and Previous WFOE were not available, the Group’s income tax expenses would have been nil, which would have no impact on the basic and diluted net loss per ordinary share attributable to the Company, for the three years ended December 31, 2018. Deferred taxes reflect the tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The components of deferred taxes are as follows: As of December 31, 2017 2018 RMB RMB Non-current deferred tax assets Accrued expenses 5,108 13,270 Advertising expenses carry-forwards 87,600 87,600 Net operating loss carry-forwards 117,031 285,018 Total non-current deferred tax assets 209,739 385,888 Less: valuation allowance (209,739 ) (385,888 ) Non-current deferred tax assets, net — — Total non-current deferred tax liabilities — — As of December 31, 2018, the Company’ subsidiaries, VIEs and VIEs’ subsidiaries registered in the PRC have total net operating loss carry forwards of RMB1,677,243, which would expire on various dates through December 31, 2019 to December 31, 2028. The authoritative guidance requires that the Group recognizes the impact of a tax position in the financial statements if that position is more likely than not of being sustained upon audit by the tax authority, based on the technical merits of the position. Under PRC laws and regulations, arrangements and transactions among related parties may be subject to examination by the PRC tax authorities. If the PRC tax authorities determine that the contractual arrangements among related companies do not represent a price under normal commercial terms, they may make adjustments to the companies’ income and expenses. A transfer pricing adjustment could result in additional tax liabilities. The Group did not have any significant unrecognized uncertain tax positions as of and for the years ended December 31, 2016, 2017 and 2018. In addition, uncertainties exist with respect to how the current income tax law in the PRC applies to the Group’s overall operations, and more specifically, with regard to tax residency status. The New EIT Law includes a provision specifying that legal entities organized outside of the PRC will be considered residents for Chinese income tax purposes if the place of effective management or control is within the PRC. The implementation rules to the New EIT Law provide that non-resident legal entities will be considered PRC residents if substantial and overall management and control over the manufacturing and business operations, personnel, accounting and properties, occurs within the PRC. Despite the present uncertainties resulting from the limited PRC tax guidance on the issue, the Group does not believe that the legal entities organized outside of the PRC within the Group should be treated as residents for EIT law purposes. If the PRC tax authorities subsequently determine that the Company and its subsidiaries registered outside the PRC should be deemed resident enterprises, the Company and its subsidiaries registered outside the PRC will be subject to the PRC income taxes, at a rate of 25%.

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Net Loss Per Share	18. NET LOSS PER SHARE For the purpose of calculating net loss per share as a result of the 2017 Reorganization as described in Note 1, the number of ordinary shares used in the calculation reflects the outstanding ordinary shares of the Company in 2017 as if the Group’s 2017 Reorganization took place on January 1, 2016: As of December 31, 2016 2017 2018 RMB RMB RMB Numerator: Net loss attributable to Sunlands Technology Group used in basic and diluted net loss per share: Net loss attributable to ordinary shareholders (253,567 ) (918,578 ) (927,022 ) Denominator: Weighted average ordinary shares outstanding used in computing basic and diluted net loss per share 3,818,618 3,945,864 6,294,870 Net loss per share Basic and diluted (66.40 ) (232.80 ) (147.27 ) Given the Company's loss making position for the years ended December 31, 2016, 2017 and 2018, the effect of potential issuances of shares for the convertible redeemable preferred shares and share options would be anti-dilutive: (1) The outstanding 520,161 Series A Preferred Shares were not considered in the computation of diluted net loss per share for the year ended December 31, 2016 ; (2) The outstanding 954,274 Series A Preferred Shares, 826,389 Series B Preferred Shares and 141,264 Series B+ Preferred Shares were not considered in the computation of diluted net loss per share for the year ended December 31, 2017; (3) 51,831 share options were not considered in the computation of diluted net loss per share for the year ended December 31, 2018.

Amounts Due From_To Related Par

Amounts Due From/To Related Parties	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Amounts Due From/To Related Parties	19. AMOUNTS DUE FROM/TO RELATED PARTIES (1) The table below sets forth the major related parties and their relationship with the Group. Name of related parties Relationship with the Group Shangde Jiaxun Entity controlled by the Founder and the CEO (Note 1) ELITE CONCEPT HOLDINGS LIMITED Class A Ordinary Shares holder Shanghai Chuang Ji Investment Center (Limited Partnership) (“Shanghai Chuang Ji”) Class A Ordinary Shares holder Shenzhen Xingwang Hulian II Investment Center (Limited Partnership) (“Shenzhen Xingwang”) Class A Ordinary Shares holder (2) The related party transactions were as follows: For the years ended December 31, 2016 2017 2018 RMB RMB RMB Disposal of a subsidiary to a related party — 1,000 — In October 2017, the Group disposed a subsidiary to Shangde Jiaxun with a total consideration of RMB1,000 and a gain of RMB178 was recorded in the Group’s consolidated statement of operations 19. AMOUNTS DUE FROM/TO RELATED PARTIES - continued (3) As of December 31, 2017 and 2018, the aggregate amounts due from related parties were set forth below: As of December 31, 2017 2018 RMB RMB Shangde Jiaxun (i) 8,018 — ELITE CONCEPT HOLDINGS LIMITED (ii) 162,000 — Shanghai Chuang Ji (ii) 80,000 — Shenzhen Xingwang (ii) 78 — 250,096 — (i) The balances as of December 31, 2017 included the consideration receivable of RMB1,000 from disposal of a subsidiary. The remaining balance of RMB7,018 were interest-free, unsecured and repayable on demand. The balance as of December 31, 2017 was fully repaid in February 2018. (ii) The balances as of December 31, 2017 represented the original investments of RMB242,078 in Series A Equity Interest withdrew from Beijing Sunlands by certain Series A Preferred Shareholders which were reinvested in full to the Company in January 2018 (Note 13). (4) As of December 31, 2017 and 2018, the aggregate amounts due to related parties were both nil.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	20. COMMITMENTS AND CONTINGENCIES Operating lease commitments Future minimum payments under non-cancelable operating leases related to offices and public displays with initial terms of one-year or longer consisted of the following at December 31, 2018: RMB 2019 110,796 2020 97,949 2021 90,347 2022 83,251 2023 and thereafter 698,995 1,081,338 Payments under operating leases are expensed on the straight-line basis over the periods of their respective leases. For the years ended December 31, 2016, 2017 and 2018, the total rental expenses for all operating leases amounted to RMB53,714, RMB65,214 and RMB107,331, respectively. Investment commitment The Group was obligated to pay RMB25,000 for the long-term investments as of December 31, 2018.

Segment Reporting

Segment Reporting	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Segment Reporting	21. SEGMENT REPORTING The Group’s chief operating decision maker (“CODM”) has been identified as the Chief Executive Officer of the Group, who reviews financial information of operating segments when making decisions about allocating resources and assessing performance of the Group. An operating segment is a component of the Group that engages in business activities from which it may earn revenues and incur expenses, and is identified on the basis of the internal financial reports that are provided to and regularly reviewed by the Group’s CODM. For the years ended December 31, 2016, 2017 and 2018, the Group’s CODM reviewed the financial information of the education business carried out by the Group on a consolidated basis. The Group has one operating segment, which is the provision of online education service. The Group operates solely in the PRC and all of the Group’s long-lived assets are located in the PRC.

Employee Defined Contribution P

Employee Defined Contribution Plan	12 Months Ended
	Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Employee Defined Contribution Plan	22. EMPLOYEE DEFINED CONTRIBUTION PLAN Full time employees of the Group in the PRC participate in a government mandated defined contribution plan, pursuant to which certain pension benefits, medical care, employee housing fund and other welfare benefits are provided to employees. Chinese labor regulations require that the PRC subsidiaries of the Group make contributions to the government for these benefits based on certain percentages of the employees’ salaries. The Group has no legal obligation for the benefits beyond the contributions made. The total amounts for such employee benefits, which were expensed as incurred, were RMB64,189, RMB164,775 and RMB228,376, for the years ended December 31, 2016, 2017 and 2018, respectively.

Restricted Net Assets

Restricted Net Assets	12 Months Ended
	Dec. 31, 2018
Restricted Net Assets [Abstract]
Restricted Net Assets	23. RESTRICTED NET ASSETS Relevant PRC statutory laws and regulations permit payments of dividends by the Group’s PRC subsidiaries only out of their retained earnings, if any, as determined in accordance with PRC accounting standards and regulations. The results of operations reflected in the financial statements prepared in accordance with U.S. GAAP differ from those reflected in the statutory financial statements of the Company’s subsidiaries. In accordance with the Regulations on Enterprises with Foreign Investment of China and their articles of association, a foreign invested enterprise established in the PRC is required to provide certain statutory reserves, namely general reserve fund, the enterprise expansion fund and staff welfare and bonus fund which are appropriated from net profit as reported in the enterprise’s PRC statutory accounts, which is included in retained earnings accounts in equity section of the consolidated balance sheets. A wholly-owned foreign invested enterprise is required to allocate at least 10% of its annual after-tax profit to the general reserve until such reserve reaches 50% of its respective registered capital based on the enterprise’s PRC statutory accounts. Appropriations to the enterprise expansion fund and staff welfare and bonus fund are at the discretion of the board of directors for all foreign invested enterprises. The aforementioned reserves can only be used for specific purposes and are not distributable as cash dividends. If any PRC subsidiary incur debt on its own behalf in the future, the instruments governing the debt may restrict their ability to pay dividends or make other payments to the Group. Any limitation on the ability of the PRC subsidiaries to distribute dividends or other payments to their respective shareholders could materially and adversely limit the ability to grow, make investments or acquisitions that could be beneficial to pay dividends. Additionally, in accordance with the Company Law of the PRC, a domestic enterprise is required to provide statutory common reserve at least 10% of its annual after-tax profit until such reserve reaches 50% of its respective registered capital based on the enterprise’s PRC statutory accounts. The Group’s provision for the statutory common reserve is in compliance with the aforementioned requirement of the Company Law. A domestic enterprise is also required to provide for discretionary surplus reserve, at the discretion of the board of directors, from the profits determined in accordance with the enterprise’s PRC statutory accounts. The aforementioned reserves can only be used for specific purposes and are not distributable as cash dividends. Because the Group’s entities in the PRC can only be paid out of distributable profits reported in accordance with PRC accounting standards, the Group’s entities in the PRC are restricted from transferring a portion of their net assets to the Company. The restricted amounts include the paid-in capital and statutory reserves of the Group’s entities in the PRC. The aggregate amount of paid-in capital and statutory reserves, which is the amount of net assets of the Group’s entities in the PRC (mainland) not available for distribution, were RMB1,986 as of December 31, 2018.

Condensed Financial Information

Condensed Financial Information Of Parent Company	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Of Parent Company Only Disclosure [Abstract]
Condensed Financial Information Of Parent Company	CONDENSED FINANCIAL INFORMATION OF PARENT COMPANY BALANCE SHEETS (Amounts in thousands, except for share and per share data) As of December 31, 2017 2018 2018 RMB RMB US$ ASSETS Cash and cash equivalents 155,652 1,086,521 158,028 Short-term investments — 441,513 64,215 Prepaid expenses and other current assets — 11,950 1,738 Amounts due from subsidiaries 509,657 695,194 101,112 Amounts due from related parties 242,078 — — Total current assets 907,387 2,235,178 325,093 TOTAL ASSETS 907,387 2,235,178 325,093 LIABILITIES, MEZZANINE EQUITY AND SHAREHOLDERS’ DEFICIT LIABILITIES Current liabilities Accrued expenses and other current liabilities 81 6,268 912 Total current liabilities 81 6,268 912 Non-current liabilities Investment in subsidiaries 1,524,565 2,556,801 371,871 Other non-current liabilities — 11,228 1,633 Total non-current liabilities 1,524,565 2,568,029 373,504 TOTAL LIABILITIES 1,524,646 2,574,297 374,416 MEZZANINE EQUITY Series A convertible redeemable preferred shares 292,000 — — Series B convertible redeemable preferred shares 601,605 — — Series B+ convertible redeemable preferred shares 131,104 — — TOTAL MEZZANINE EQUITY 1,024,709 — — SHAREHOLDERS’ DEFICIT Ordinary shares (par value of US$0.00005, 1,000,000,000 shares authorized; 4,329,000 and nil shares issued and outstanding as of December 31, 2017 and 2018, respectively) 1 — — Class A ordinary shares (par value of US$0.00005, 796,062,195 shares authorized; nil and 1,818,383 shares issued as of December 31, 2017 and 2018, respectively; nil and 1,773,301 shares outstanding as of December 31, 2017 and 2018, respectively) — 1 — Class B ordinary shares (par value of US$0.00005, 826,389 shares authorized; nil and 826,389 shares issued and outstanding as of December 31, 2017 and 2018, respectively) — — — Class C ordinary shares (par value of US$0.00005, 203,111,416 shares authorized; nil and 4,265,286 shares issued and outstanding as of December 31, 2017 and 2018, respectively) — 1 — Treasury stock — — — Additional paid-in capital 289,674 2,391,822 347,876 Accumulated other comprehensive (loss)/income (8,759 ) 118,827 17,283 Accumulated deficit (1,922,884 ) (2,849,770 ) (414,482 ) TOTAL SHAREHOLDERS’ DEFICIT (1,641,968 ) (339,119 ) (49,323 ) TOTAL LIABILITIES, MEZZANINE EQUITY AND SHAREHOLDERS’ DEFICIT 907,387 2,235,178 325,093 ADDITIONAL INFORMATION—FINANCIAL STATEMENT SCHEDULE I CONDENSED FINANCIAL INFORMATION OF PARENT COMPANY STATEMENTS OF OPERATIONS (Amounts in thousands, except for share and per share data) For the years ended December 31, 2016 2017 2018 RMB RMB RMB US$ Cost of revenues — (19,244 ) (475 ) (69 ) Gross profit — (19,244 ) (475 ) (69 ) Operating expenses Sales and marketing expenses — (75,237 ) (820 ) (119 ) General and administrative expenses (4 ) (194,878 ) (15,335 ) (2,230 ) Total operating expenses (4 ) (270,115 ) (16,155 ) (2,349 ) Loss from operations (4 ) (289,359 ) (16,630 ) (2,418 ) Interest income — 1,592 33,525 4,876 (Loss)/profit before income tax expenses (4 ) (287,767 ) 16,895 2,458 Income tax expenses — — — — Loss from investment in subsidiaries (253,563 ) (630,947 ) (943,781 ) (137,268 ) Net loss (253,567 ) (918,714 ) (926,886 ) (134,810 ) ADDITIONAL INFORMATION—FINANCIAL STATEMENT SCHEDULE I CONDENSED FINANCIAL INFORMATION OF PARENT COMPANY STATEMENT OF CHANGES IN SHAREHOLDERS’ DEFICIT (Amounts in thousands, except for share and per share data) Class A Class B Class C Additional Treasury Accumulated other Total Ordinary shares Ordinary shares Ordinary shares Ordinary shares paid-in stock comprehensive Accumulated shareholders' Shares Amounts Shares Amounts Shares Amounts Shares Amounts capital Shares Amounts (loss)/income deficit deficit RMB RMB RMB RMB RMB RMB RMB RMB RMB Balance as of January 1, 2016 3,818,618 1 — — — — — — 911 — — — (372,656 ) (371,744 ) Net loss for the year — — — — — — — — — — — — (253,567 ) (253,567 ) Recapitalization in connection with the Group’s 2016 reorganization — — — — — — — — — — — — (293,644 ) (293,644 ) Capital contribution from equity shareholders — — — — — — — — 30,000 — — — — 30,000 Balance as of December 31, 2016 3,818,618 1 — — — — — — 30,911 — — — (919,867 ) (888,955 ) Net loss for the year — — — — — — — — — — — — (918,714 ) (918,714 ) Capital contribution from a noncontrolling shareholder — — — — — — — — — — — — — — Repurchase of equity from shareholders — — — — — — — — (30,000 ) — — — (41,303 ) (71,303 ) Cash dividend to a Series A convertible redeemable preferred shareholder — — — — — — — — — — — — (43,000 ) (43,000 ) Shares issuance in relation to share-based compensation 510,382 — — — — — — — — — — — — — Share-based compensation — — — — — — — — 288,763 — — — — 288,763 Foreign currency translation adjustments — — — — — — — — — — — (8,759 ) — (8,759 ) Balance as of December 31, 2017 4,329,000 1 — — — — — — 289,674 — — (8,759 ) (1,922,884 ) (1,641,968 ) Net loss for the year — — — — — — — — — — — — (926,886 ) (926,886 ) Issuance of ordinary shares, net of issuance cost of 80,128 — — 659,131 — — — — — 1,109,517 — — — — 1,109,517 Conversion of convertible redeemable preferred shares upon initial public offering (4,329,000 ) (1 ) 1,159,252 1 826,389 — 4,265,286 1 1,024,708 — — — — 1,024,709 Share repurchase — — (45,082 ) — — — — — (34,828 ) 45,082 — — — (34,828 ) Share-based compensation — — — — — — — — 2,751 — — — — 2,751 Foreign currency translation adjustments — — — — — — — — — — — 127,586 — 127,586 Balance as of December 31, 2018 in RMB — — 1,773,301 1 826,389 — 4,265,286 1 2,391,822 45,082 — 118,827 (2,849,770 ) (339,119 ) Balance as of December 31, 2018 in USD — — 1,773,301 — 826,389 — 4,265,286 — 347,876 45,082 — 17,283 (414,482 ) (49,323 ) Note: The number of ordinary shares reflects the outstanding ordinary shares of the Company as if the Group’s 2017 reorganization took place on January 1, 2016. . ADDITIONAL INFORMATION—FINANCIAL STATEMENT SCHEDULE I CONDENSED FINANCIAL INFORMATION OF PARENT COMPANY STATEMENTS OF CASH FLOWS (Amounts in thousands, except for share and per share data) For the years ended December 31, 2016 2017 2018 RMB RMB RMB US$ CASH FLOWS FROM OPERATING ACTIVITIES Net loss (253,567 ) (918,714 ) (926,886 ) (134,810 ) Adjustments to reconcile net loss to net cash generated from operating activities: Share-based compensation — 288,763 3,851 560 Loss from investment in subsidiaries 253,563 813,313 1,032,235 150,132 Amounts due to subsidiaries — (751,735 ) (185,537 ) (26,985 ) Prepaid expenses and other current assets — — (19,276 ) (2,804 ) Other non-current liabilities — — 11,228 1,633 Accrued expenses and other current liabilities 4 75 4,231 615 Net cash used in operating activities — (568,298 ) (80,154 ) (11,659 ) CASH FLOWS FROM INVESTING ACTIVITIES Purchase of short-term investments — — (814,539 ) (118,470 ) Disposal of short-term investments — — 396,852 57,720 Net cash used in investing activities — — (417,687 ) (60,750 ) CASH FLOWS FROM FINANCING ACTIVITIES Amounts due from related parties — — 245,654 35,729 Payment for share repurchase — — (33,971 ) (4,941 ) Proceeds from initial public offering, net of issuance cost of 80,128 — — 1,109,517 161,373 Capital contribution from series B and B+ convertible redeemable preferred shareholders — 732,709 — — Net cash generated from financing activities — 732,709 1,321,200 192,161 Effect of exchange rate charges — (8,759 ) 107,510 15,637 Net increase in cash and cash equivalents — 155,652 930,869 135,389 Cash and cash equivalents at beginning of the year — — 155,652 22,639 Cash and cash equivalents at end of the year — 155,652 1,086,521 158,028 ADDITIONAL INFORMATION—FINANCIAL STATEMENT SCHEDULE I CONDENSED FINANCIAL INFORMATION OF PARENT COMPANY NOTES TO FINANCIAL STATEMENTS (Amounts in thousands, except for share and per share data) 1. Schedule I has been provided pursuant the requirements of Rule 12-04(a) and 5-04(c) of Regulation S-X, which require condensed financial information as to the financial position, changes in financial position and results of operations of a parent company as of the same dates and for the same periods for which audited consolidated financial statements have been presented when the restricted net assets of consolidated subsidiaries exceed 25 percent of consolidated net assets as of the end of the most recently completed fiscal year. 2. The condensed financial information of Sunlands Technology Group has been prepared using the same accounting policies as set out in the accompanying consolidated financial statements except that the equity method has been used to account for investments in its subsidiaries. 3. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted. The footnote disclosures contain supplemental information relating to the operations of the Group and, as such, these statements should be read in conjunction with the notes to the Consolidated Financial Statements of the Group. No dividend was paid by the Group's subsidiaries to their parent company in 2016, 2017 and 2018. 4. As of December 31, 2018, there were no material contingencies, significant provisions of long-term obligations, and mandatory dividend or redemption requirements of redeemable shares or guarantees of the Group, except for those which have been separately disclosed in the Consolidated Financial Statement, if any.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Basis of presentation and use of estimates	Basis of presentation and use of estimates The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosures of contingent assets and liabilities at the balance sheet dates and the reported amounts of revenues and expenses during the reporting periods. Significant estimates and assumptions reflected in the Group’s financial statements include, but are not limited to, consolidation of VIEs, valuation allowance for deferred tax assets, the variable consideration to be earned under refundable course model, useful lives of property and equipment, impairment of long-term assets and valuation of share-based compensation. Actual results could materially differ from those estimates.
Principles of consolidation	Principles of consolidation The consolidated financial statements include the financial statements of the Company and its subsidiaries, and VIEs and VIEs’ subsidiaries. All intercompany transactions and balances were eliminated upon consolidation.
Foreign currency translation and transactions	Foreign currency translation and transactions The Group’s reporting currency is Renminbi (“RMB”). The functional currency of the subsidiaries incorporated outside the mainland China is United States dollar (“US dollar” or “US$”). The functional currency of all the other subsidiaries and the VIEs and VIEs’ subsidiaries is RMB. Monetary assets and liabilities denominated in currencies other than the applicable functional currencies are translated into the functional currencies at the prevailing rates of exchange at the balance sheet date. Nonmonetary assets and liabilities are remeasured into the applicable functional currencies at historical exchange rates. Revenues and expenses are translated using the average rate of exchange in effect during the reporting period. Translation adjustments are reported and shown as a separate component of other comprehensive loss in the consolidated statements of changes in shareholders’ deficit and the consolidated statements of comprehensive loss. Transactions in currencies other than the functional currencies during the year are converted into the applicable functional currencies at the applicable rates of exchange prevailing at the dates of the transactions. Transaction gains and losses are recorded in the consolidated statements of operations.
Convenience Translation	Convenience Translation The Group’s business is primarily conducted in China and all of the revenues are denominated in RMB. However, periodic reports made to shareholders will include current period amounts translated into US dollars using the then current exchange rates, for the convenience of the readers. Translations of balances in the consolidated balance sheets, and the related consolidated statements of operations, shareholders’ deficit and cash flows from RMB into US dollars as of and for the year ended December 31, 2018 are solely for the convenience of the readers and were calculated at the rate of US$1.00= RMB6
Cash and cash equivalents	Cash and cash equivalents Cash and cash equivalents comprise cash at banks and on hand and term deposits, which have original maturities of three months or less when purchased and are subject to an insignificant risk of changes in value. The carrying value of cash equivalents approximates market value.
Short-term investments	Short-term investments Short-term investments consist of financial products with unsecured principal purchased from commercial banks and financial institutions which have original maturities of less than one year. The carrying amount of these short-term investments approximates their fair values due to the short-term maturities of these investments and are carried at cost. The Group reviews its short-term investments for impairment whenever an event or circumstance indicates that impairment has occurred. The Group considers available quantitative and qualitative evidence in evaluating the potential impairment of its short-term investments. An impairment charge is recorded in the consolidated statements of operations if the carrying amount of an investment exceeds the investment’s fair value
Long-term investments	Long-term investments Investee companies over which the Group has the ability to exercise significant influence, but does not have a controlling interest through investment in common shares or in-substance common shares, are accounted for using the equity method. Significant influence is generally considered to exist when the Group has an ownership interest in the voting stock of the investee between 20% and 50%, and other factors, such as representation on the investee’s board of directors, voting rights and the impact of commercial arrangements, are also considered in determining whether the equity method of accounting is appropriate. For certain investments in limited partnerships, where the Group holds less than a 20% equity or voting interest, the Group may also have significant influence. 2. SIGNIFICANT ACCOUNTING POLICIES - continued Long-term investments - continued Under the equity method of accounting, the Group initially records its investment at cost and subsequently recognizes the Group’s proportionate share of each equity investee’s net income or loss after the date of investment into earnings and adjusts the investment carrying amount accordingly. The Group reviews its equity method investments for impairment whenever an event or circumstance indicates that any other-than-temporary impairment has occurred. The Group considers available quantitative and qualitative evidence in evaluating potential impairment of its equity method investments. An impairment charge is recorded when the carrying amount of the investment exceeds its fair value and this condition is determined to be other-than-temporary.
Fair value	Fair value Fair value is the price that would be received from selling an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value measurements for assets and liabilities required or permitted to be recorded at fair value, the Group considers the principal or most advantageous market in which it would transact and it considers assumptions that market participants would use when pricing the asset or liability. Authoritative literature provides a fair value hierarchy which prioritizes the inputs to valuation techniques used to measure fair value into three broad levels. The level in the hierarchy within which the fair value measurement in its entirety falls is based upon the lowest level of input that is significant to the fair value measurement as follows: Level 1 Level 1 applies to assets or liabilities for which there are quoted prices in active markets for identical assets or liabilities. Level 2 Level 2 applies to assets or liabilities for which there are inputs other than quoted prices included within Level 1 that are observable for the asset or liability such as quoted prices for similar assets or liabilities in active markets; quoted prices for identical assets or liabilities in markets with insufficient volume or infrequent transactions (less active markets); or model-derived valuations in which significant inputs are observable or can be derived principally from, or corroborated by, observable market data. Level 3 Level 3 applies to assets or liabilities for which there are unobservable inputs to the valuation methodology that are significant to the measurement of the fair value of the assets or liabilities.
Financial instruments	Financial instruments The Group’s financial instruments consist primarily of cash and cash equivalents, short-term investments, amounts due from related parties, other current liabilities and long-term debt. The carrying amount of long-term debt approximates fair value as its interest rates are at the same level of current market yield for comparable debts. The carrying amounts of other financial instruments approximate their fair values due to short-term maturities
Property and equipment, net	Property and equipment, net Property and equipment are stated at cost and are depreciated using the straight-line method over the estimated useful lives of the assets, as follows: Category Estimated useful life Buildings 36-37 years Leasehold and buildings improvements Shorter of lease term or expected useful life Electronic and office equipment 3-5 years 2. SIGNIFICANT ACCOUNTING POLICIES - continued Property and equipment, net - continued Repair and maintenance costs are charged to expense as incurred, whereas the cost of renewals and betterment that extends the useful lives of property and equipment are capitalized as additions to the related assets. Retirements, sales and disposals of assets are recorded by removing the cost and accumulated depreciation from the asset and accumulated depreciation accounts with any resulting gain or loss reflected in the consolidated statements of operations.
Intangible assets, net	Intangible assets, net Intangible assets are amortized using the straight-line basis over the estimated useful lives as follows: Category Estimated useful life Computer software 3 years
Impairment of long-lived assets	Impairment of long-lived assets The Group reviews its long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may no longer be recoverable. When these events occur, the Group measures impairment by comparing the carrying value of the long-lived assets to the estimated undiscounted future cash flows expected to result from the use of the assets and their eventual disposition. If the sum of the expected undiscounted cash flow is less than the carrying amount of the assets, the Group would recognize an impairment loss based on the fair value of the assets. The Group did not record any impairment losses on its long-lived assets during the years ended December 31, 2016, 2017 and 2018.
Revenue recognition, Deferred Revenue and Cost of revenue	Revenue recognition In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, “Revenue from Contracts with Customers (Topic 606).” This standard replaced existing revenue recognition rules with a comprehensive revenue measurement and recognition standard and expanded disclosure requirements. The ASU also includes guidance regarding the accounting for contract acquisition costs, which includes sales commissions. The Group has early adopted the new standard as of January 1, 2017 using the full retrospective method which requires the Group to present its financial statements for all periods as if Topic 606 had been applied to all prior periods. The Group did not apply practical expedients as provided under Topic 606. The Group follows five steps for its revenue recognition under Topic 606: (i) identify the contract(s) with a customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations in the contract, and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Group’s revenue is reported net of discount, business tax, value added tax and related surcharges. The primary sources of the Group’s revenues are as follows: Online education services For online education services, the Group provides an integrated online education service package to students, including online live streaming audio-video interactive course content, recorded previous live audio-video course content, quiz banks, online chat rooms, and educational contents. The services and goods provided in the package are highly interdependent and interrelated in the context of the contract and are only considered accessory services to the online live streaming and recorded courses which are not distinct and are not sold standalone. Therefore, the Group’s integrated online education services package is accounted for as a single performance obligation. The weighted average service period for degree- or diploma-oriented post-secondary courses and professional certification preparation and professional skills courses was 31 months and 20 months, respectively, for the year ended December 31, 2018. The transaction price of the integrated online education service package is determined by the contract amount net of any discounts. Students are offered a full, unconditional refund within 24 hours upon enrollment, and a partial refund for the undelivered courses, excluding registration fees, within 7 days . 2. SIGNIFICANT ACCOUNTING POLICIES - continued Revenue recognition – continued Online education services – continued Online education services consist of two types of revenue models—the non-refundable course model and the refundable course model. Revenues for the non-refundable course model are recognized on a straight line basis over the service period from the registration day to the day on which the service period ends. For the refundable course model, the Group provides a student the ability to apply for a refund if the student achieves certain agreed conditions. The Group estimates the variable consideration to be earned to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is resolved and recognizes revenue over time from the registration day to the day on which the service period ends on a straight line basis. The Group’s estimates of variable consideration and determination of whether to include estimated amounts in the transaction price are based largely on an assessment of the Group’s anticipated performance and all information (historical, current and forecasted) that is reasonably available. Under the non-refundable course model, for certain online courses, the service period includes a regular period plus an extended period. The Group offers students an extended period after the regular period if conditions are met. Online education services with insurance coverage since 2018 Under the non-refundable course model, for certain online courses, the Group offers a bundle service including an integrated online education service package with insurance coverage for tuition refund. If the refundable conditions are met, students could claim the insurance equal to full or partial amount of the service fee. The Group identifies that the integrated online education service package and the insurance service are two separate performance obligations as students benefit from each service on its own and they are separately identifiable in the contract. The Group records revenue generated from online education services with insurance coverage on a gross basis as the Group is acting as the principal to fulfill all obligation and control all the services transferred to the students. The Group estimates the stand-alone selling prices of each performance obligation based on the expected cost of satisfying each performance obligation plus an estimated margin for each performance obligation. Revenues for integrated online education service and the insurance coverage service are recognized based on their relative stand-alone selling price over their respective service periods on a straight line basis from the registration day to the day on which the service period ends as the students simultaneously receives and consumes the benefits provided by these two performance obligations. The Group’s deferred costs represent the unamortized incremental sales commission relating to obtaining of customers contract, and the contract liability primarily consists of deferred revenue. Student Financing The Group offers an installment payment option to students, under which the students obtain loans, from accredited credit sources (“Loan Companies”) for the purpose of satisfying the student’s tuition payment due. The borrowing student is obligated to repay the loan principal in installments over periods ranging from 3 months to 12 months to the Loan Companies, while the Group agrees with the Loan Companies to bear the student’s interest expense and service fees. The Loan Companies remit the tuition to the Group for students to complete the registration. The interest expense and service fees are recorded as a reduction of the transaction price. Commission revenue The Group earns commission revenue by providing referral services to third party education institutions. Commission revenue is recognized when the referred students registered at the third party education institutions and the tuition fees are paid, by when the performance obligation is satisfied. 2. SIGNIFICANT ACCOUNTING POLICIES - continued Deferred Revenue Revenues related to the Group’s online courses are recognized over time. Deferred revenue consists of tuition fees received from students for which services have not yet been provided to students. Cost of revenue Cost of revenues consist of expenditures incurred in the generation of the Group’s revenue, includes but not limited to salaries and benefits paid to teachers, related rental expenses, server management costs, bandwidth costs, payment processing costs, insurance cost, depreciations for property and equipment and amortizations for intangible assets.
Business taxes	Business taxes Prior to May 2016, Beijing Sunlands and its subsidiaries were subject to business tax and related surcharges at a rate of 3.36% on revenues related to educational services and 5.6% on non-educational services, respectively. The net revenues are presented net of those taxes incurred.
Value added taxes (“VAT”)	Value added taxes (“VAT”) Beginning in May 2016, in accordance with Tax rule (Cai Shui [2016] No. 68), the non-academic educational programs and services are subject to a simple VAT collection method at a rate of 3%. Entities which are subject to the tax rate of 3% are not allowed to offset qualified input VAT paid to suppliers against their output VAT liabilities. The Group’s educational services, which were previously subject to business tax, are therefore subject to VAT at the rate of 3%. For Tianjin Shangde, the educational services are subject to VAT at the rate of 6%. For non-educational services, the VAT rate is 6%, in accordance with Tax rule (Cai Shui [2016] No. 36).
Product development expenses	Product development expenses Product development expenses primarily consist of (i) salaries and benefits for innovation and development of course content, product and technology development personnel, and (ii) office rental, general expenses and depreciation and amortization expenses associated with the product development activities. The Group’s product development activities primarily consist of the development and enhancement of the Group’s educational content, applications and platforms. The Group has expensed all product development expenses when incurred.
Sales commission	Sales commission The incremental sales commission relating to obtaining of the customer contract and expected to be recovered is accounted for as an incremental cost of obtaining a contract pursuant to ASC340-40 and is capitalized as deferred costs when incurred. The capitalized cost is amortized in the same manner as the revenue recognized and is included in “sales and marketing expenses” in the consolidated statements of operations. Other sales commission incurred regardless of whether the contract was obtained is recognized as an expense when incurred.
Advertising expenditure	2. SIGNIFICANT ACCOUNTING POLICIES - continued Advertising expenditure Advertising expenditure, mainly includes search engine marketing and mobile marketing expenses, is expensed when incurred and is included in sales and marketing expenses in the consolidated statements of operations. Advertising expenses were RMB188,516, RMB499,294 and RMB983,012 for the years ended December 31, 2016, 2017 and 2018, respectively.
Sales and marketing expenses	Sales and marketing expenses Sales and marketing expenses primarily consist of (i) salaries and benefits for sales and marketing personnel, (ii) search engine marketing and mobile marketing expenses and other advertising expenses, (iii) office rental, general expenses and depreciation and amortization expenses associated with the sales and marketing activities.
Operating leases	Operating leases Leases where substantially all the rewards and risk of assets remain with the leasing company are accounted for as operating leases. Payments made under operating leases are charged to the consolidated statements of operations on a straight-line basis over the lease term.
Government Subsidies	Government subsidies For the government subsidies not subject to further performance obligations or future returns, the Group records the amounts as other income when received from local government authority. Whereas for the government subsidies with future performance obligations, the Group recognizes those as liabilities when received until the performances obligations have been met at which time, those are recognized as other income. Government subsidies received and recorded as other income amounted to RMB1,601, RMB3,223 and RMB28,688 for the years ended December 31, 2016, 2017 and 2018, respectively.
Income taxes	Income taxes Current income taxes are provided for in accordance with the laws of the relevant tax authorities. Deferred income taxes are recognized when temporary differences exist between the tax bases of assets and liabilities and their reported amounts in the financial statements. Net operating loss carry forwards and credits are applied using enacted statutory tax rates applicable to future years. Deferred tax assets are reduced by a valuation allowance when, in the opinion of management, it is more-likely-than-not that a portion of or all of the deferred tax assets will not be realized. The impact of an uncertain income tax position is recognized at the largest amount that is more-likely-than-not to be sustained upon audit by the relevant tax authority. An uncertain income tax position will not be recognized if it has less than a 50% likelihood of being sustained. Interest and penalties on income taxes will be classified as a component of the provisions for income taxes.
Comprehensive loss	Comprehensive loss Comprehensive loss includes net loss and foreign currency translation adjustments and is reported in the consolidated statements of comprehensive loss. The Group presents the components of net loss, the components of other comprehensive loss and total comprehensive loss in two separate but consecutive statements.
Net loss per share	2. SIGNIFICANT ACCOUNTING POLICIES - continued Net loss per share Prior to IPO, basic net loss per share is computed by dividing net loss attributable to ordinary shareholders of the Company by the weighted average number of ordinary shares outstanding during the year using the two-class method. The holders of the convertible redeemable preferred shares are entitled to share dividends on a pro rata basis, as if their shares had been converted into ordinary shares. Accordingly, the Company has used the two-class method in computing net loss per share. Under the two-class method, net loss is allocated on a pro rata basis to each class of ordinary shares and other participating securities based on their participating rights. After IPO, basic net loss per share is computed by dividing net loss attributable to ordinary shareholders of the Company by the weighted average number of common shares outstanding during the year. Diluted net loss per share reflects the potential dilution that could occur if securities or other contracts to issue common shares were exercised into common shares. To calculate the number of shares for diluted loss per share, the effect of the share options is computed using the treasury stock method. As the Company was loss making for the years ended December 31, 2016, 2017 and 2018, the effect of potential issuances of shares for the convertible redeemable preferred shares and share options would be anti-dilutive, and therefore basic and diluted losses per share are the same in those periods.
Share-based compensation	Share-based compensation Share-based compensation with employees is measured based on the grant date fair value of the equity instrument. Share-based compensation expenses, net of forfeitures, are recognized over the requisite service period based on a straight-line basis with a corresponding impact reflected in additional paid-in capital. Share-based compensation awards which require the issuance of a variable number of shares to settle a fixed monetary amount are recorded as liabilities.
Significant Risks and Uncertainties	Significant risks and uncertainties Foreign currency risk RMB is not a freely convertible currency. The State Administration for Foreign Exchange, under the authority of the People’s Bank of China, controls the conversion of RMB into foreign currencies. The value of RMB is subject to changes in central government policies and to international economic and political developments affecting supply and demand in the China Foreign Exchange Trading System market. The cash and cash equivalents of the Group included aggregate amounts of RMB104,244 and RMB157,103, which were denominated in RMB at December 31, 2017 and 2018, representing 18.6% and 12.6% of the cash and cash equivalents at December 31, 2017 and 2018, respectively. Concentration of credit risk Financial instrument that potentially expose the Group to significant concentration of credit risk primarily consist of cash and cash equivalents, short-term investments, amounts due from related parties and prepaid expenses and other current assets. The Group places its cash and cash equivalents and short-term investments in financial institutions with high credit ratings. There are no revenues from customers which individually represent greater than 10% of the total net revenues for any year of the three years period ended December 31, 2018.
Newly adopted accounting pronouncements	Newly adopted accounting pronouncements In January 2016, the FASB issued a new pronouncement ASU 2016-01 Financial Instruments-Overall: Recognition and Measurement of Financial Assets and Financial Liabilities. The ASU requires equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) to be measured at fair value with changes in fair value recognized in net income. The ASU also requires an entity to present separately in other comprehensive income the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments. 2. SIGNIFICANT ACCOUNTING POLICIES - continued Newly adopted accounting pronouncements - continued ASU 2016-01 was further amended in February 2018 by ASU 2018-03, "Technical Corrections and Improvements to Financial Instruments—Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities". This update was issued to clarify certain narrow aspects of guidance concerning the recognition of financial assets and liabilities established in ASU 2016-01. This includes an amendment to clarify that an entity measuring an equity security using the measurement alternative may change its measurement approach to a fair valuation method in accordance with Topic 820, Fair Value Measurement, through an irrevocable election that would apply to that security and all identical or similar investments of the same issued. ASU 2016-01 and ASU 2018-03 are effective for public companies for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. Adoption of the amendment must be applied by means of a cumulative-effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption, except for amendments related to equity instruments that do not have readily determinable fair values which should be applied prospectively. The Group has adopted the new standard as of January 1, 2018, which did not result in a material impact on its consolidated financial statements.
Recent accounting pronouncements not yet adopted	Recent accounting pronouncements not yet adopted In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). The guidance supersedes existing guidance on accounting for leases with the main difference being that operating leases are to be recorded in the statement of financial position as right-of-use assets and lease liabilities, initially measured at the present value of the lease payments. For operating leases with a term of 12 months or less, a lessee is permitted to make an accounting policy election not to recognize lease assets and liabilities. For public business entities, the guidance is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early application of the guidance is permitted. In July 2018, the FASB issued ASU 2018-10, Codification Improvements to Topic 842, Leases. The amendments in this ASU are of a similar nature to the items typically addressed in the Codification improvements project. However, the Board decided to issue a separate ASU for the improvements related to Accounting Standards Update No. 2016-02, Leases (Topic 842), to increase stakeholders’ awareness of the amendments and to expedite the improvements. The amendments in this ASU affect narrow aspects of the guidance issued in ASU 2016-02. For entities that have early adopted Topic 842, the amendments in this Update should be effective upon issuance of the final Update and the transition requirements should be the same as those in Topic 842. For entities that have not adopted Topic 842, the effective date and transition requirements of the amendments should be the same as the effective date and transition requirements in Topic 842. In July 2018, the FASB issued ASU 2018-11, Leases (Topic 842): Targeted Improvements. The amendments in this ASU related to separating components of a contract affect the amendments in ASU 2016-02, which are not yet effective but can be early adopted. For entities that have not adopted Topic 842 before the issuance of this ASU, the effective date and transition requirements for the amendments in this ASU related to separating components of a contract are the same as the effective date and transition requirements in ASU 2016-02. All entities, including early adopters that elect the practical expedient related to separating components of a contract in this ASU must apply the expedient, by class of underlying asset, to all existing lease transactions that qualify for the expedient at the date elected. Specifically, under the amendments in ASU 2018-11, (1) entities may elect not to recast the comparative periods presented when transitioning to ASC 842 and (2) lessors may elect not to separate lease and nonlease components when certain conditions are met. Before ASU 2018-11 was issued, transition to the new lease standard required application of the new guidance at the beginning of the earliest comparative period presented in the financial statements. The Group has substantially completed its evaluation of the effect of the adoption of this ASU and expects the adoption will result in an increase in the assets and liabilities on the consolidated balance sheet for the operating leases and will have insignificant impact on its consolidated statements of operations and cash flows. 2. SIGNIFICANT ACCOUNTING POLICIES - continued Recent accounting pronouncements not yet adopted - continued In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820)—Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement. The amendments in this ASU improve the effectiveness of fair value measurement disclosures and modify the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement, based on the concepts in FASB Concepts Statement, Conceptual Framework for Financial Reporting—Chapter 8: Notes to Financial Statements, including the consideration of costs and benefits. The amendments in this ASU are effective for all entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. Early adoption is permitted. The Group is in the process of evaluating the impact that this guidance will have on its consolidated financial statements. In October 2018, the FASB issued ASU No. 2018-17, Consolidation (Topic 810): Targeted Improvements to Related Party Guidance for Variable Interest Entities (“VIE”). The guidance was issued in response to stakeholders’ observations that Topic 810, Consolidation, could be improved in the areas of applying the VIE guidance to private companies under common control and in considering indirect interests held through related parties under common control for determining whether fees paid to decision makers and service providers are variable interests. The new standard will become effective for the Company beginning January 1, 2020, with early adoption permitted, and must be applied retrospectively with a cumulative-effect adjustment to retained earnings at the beginning of the earliest period presented. The Group is in the process of evaluating the impact that this guidance will have on its consolidated financial statements.

Organization and Basis of Pre_2

Organization and Basis of Presentation (Tables)	12 Months Ended
	Dec. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Summary of Subsidiaries VIEs and VIEs' Subsidiaries	As of December 31, 2018, details of the Company’s subsidiaries, its VIEs and VIEs’ subsidiaries were as follows: Name (1) Date of establishment/ acquisition Place of establishment Percentage of direct or indirect economic ownership Principal activities Subsidiaries: Sunlands HK October 6, 2015 HongKong 100% Investment holding Wuhan Zhibo August 2, 2017 PRC 100% Provision of technical consultation and services Tianjin Sunlands July 31, 2017 PRC 100% Provision of technical consultation and services Variable interest entities ("VIEs"): Beijing Sunlands September 27, 2013 PRC N/A* Investment holding and provision of education services Tianjin Shangde March 21, 2018 PRC N/A* Provision of education services VIEs’ subsidiaries: Beijing Shangzhi Jiaye Education Technology Co., Ltd. March 13, 2012 PRC 100% Provision of education services Beijing Shangren Chongye Education Technology Co., Ltd. September 27, 2013 PRC 100% Provision of education services Guangdong Shangde Online Education Technology Co., Ltd. October 15, 2013 PRC 100% Provision of education services Urumchi Shangde Renye Business Consulting Co., Ltd. March 10, 2015 PRC 100% Provision of education services Guangzhou Youhe Self-study Training School May 19, 2015 PRC 100% Provision of education services Beijing Bainiao Education Technology Co., Ltd. (2) March 3, 2016 PRC 100% Provision of education services Shanghai Shangchi Education Technology Co., Ltd. December 22, 2016 PRC 90% Provision of education services Beijing Shangren Side Education Technology Co., Ltd. June 2, 2017 PRC 100% Provision of education services Shanghai Shangchi Institute September 1, 2017 PRC 100% Provision of education services Guangzhou Shangzhi Side Education Technology Co., Ltd. September 28, 2017 PRC 100% Provision of education services * These entities are controlled by the Company pursuant to the contractual agreements disclosed below. (1) The English names are for identification purpose only. (2) Previously known as Beijing Shangren Chongde Education Technology Co., Ltd. The name change permit was granted by governmental authority on June 29, 2018.
Summary Financial Information of VIEs and their Subsidiaries	1. ORGANIZATION AND BASIS OF PRESENTATION - continued The VIE arrangements - continued The following financial information of the VIEs and their subsidiaries as of December 31, 2017 and 2018 and for each of the three years in the period ended December 31, 2018 was included in the accompanying consolidated financial statements after elimination of intercompany transactions and balances within the subsidiaries, VIEs and their subsidiaries: As of December 31, 2017 2018 RMB RMB Cash and cash equivalents 101,680 80,371 Short-term investments 309,070 587,051 Prepaid expenses and other current assets 38,813 46,601 Total current assets 507,410 818,480 Total assets 954,006 1,196,336 Accrued expenses and other current liabilities 223,298 241,204 Deferred revenue, current 1,325,954 1,765,085 Payables to acquire buildings 180,390 — Total current liabilities 1,729,642 2,006,289 Deferred revenue, non-current 784,474 1,520,940 Other non-current liabilities — 135 Total liabilities 2,514,116 3,527,364 For the years ended December 31, 2016 2017 2018 RMB RMB RMB Net revenues 418,910 970,162 1,973,985 Net (loss)/income (253,563 ) (606,946 ) 393,063 Net cash generated from operating activities 89,272 845,616 1,448,005 Net cash used in investing activities (117,695 ) (375,802 ) (315,198 ) Net cash generated from (used in) financing activities 47,080 (391,237 ) 8,018

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Estimated Useful Lives of Property and Equipment	Property and equipment are stated at cost and are depreciated using the straight-line method over the estimated useful lives of the assets, as follows: Category Estimated useful life Buildings 36-37 years Leasehold and buildings improvements Shorter of lease term or expected useful life Electronic and office equipment 3-5 years
Summary of Estimated Useful Lives of Intangible Assets	Intangible assets are amortized using the straight-line basis over the estimated useful lives as follows: Category Estimated useful life Computer software 3 years

Short-Term Investments (Tables)

Short-Term Investments (Tables)	12 Months Ended
	Dec. 31, 2018
Investments Debt And Equity Securities [Abstract]
Schedule of Short-Term Investment	Short-term investments consist of various financial products with unsecured principal from financial institutions in China at original maturity less than one year when purchased. While these financial products are not publicly traded, the Group estimated that their fair value approximated the costs considering their short-term maturities and high credit quality. As of December 31, 2017 2018 RMB RMB Short-term investments 353,070 1,028,564

Prepaid Expenses and Other Cu_2

Prepaid Expenses and Other Current Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Summary of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consisted of the following: As of December 31, 2017 2018 RMB RMB Prepaid and input VAT 14,440 58,234 Prepaid marketing expenses 9,059 23,756 Interest receivables (1) — 11,632 Prepaid expenses (2) 10,081 10,820 Deferred IPO expenses 5,746 — Deposits (3) 5,154 4,595 Receivables from third-party payment platforms 3,045 3,886 Staff advances 932 9,242 Others 536 2,743 Total 48,993 124,908 (1) Represented interest receivables from short-term investments (Note 3). ( 2 ) Represented the prepaid expenses for telecommunications, network, service for online live steaming, advertising and rental. ( 3 ) Represented rental deposits, deposits for search engine marketing activities and deposits for leasehold improvement of buildings which all being refundable within one year.

Deferred Costs (Tables)

Deferred Costs (Tables)	12 Months Ended
	Dec. 31, 2018
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Schedule of Movement of Deferred Costs	The movements of deferred costs for the years ended December 31, 2017 and 2018 are as follows: As of December 31, 2017 2018 RMB RMB Beginning balances (current and non-current) 25,228 98,260 Additions 121,327 374,594 Amortizations (48,213 ) (145,488 ) Impairments (82 ) (99 ) Ending balances (current and non-current) 98,260 327,267 Deferred costs, current 55,073 180,657 Deferred costs, non-current 43,187 146,610

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Summary of Property and Equipment Consisted	Property and equipment consisted of the following: As of December 31, 2017 2018 RMB RMB Leasehold and buildings improvements 40,675 91,265 Electronic and office equipment 16,061 29,936 Buildings (1) 485,588 480,271 Total cost 542,324 601,472 Less: Accumulated depreciation (17,036 ) (41,961 ) Property and equipment, net 525,288 559,511 (1) In 2017, the Group purchased two buildings in Wuhan (Building A and B) and one building in Guangzhou (Building C) with a total consideration of RMB480,271. RMB60,000 of the consideration was paid by a mortgage loan provided by a PRC bank in August 2018 (Note 12).

Intangible Assets, Net (Tables)

Intangible Assets, Net (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill And Intangible Assets Disclosure [Abstract]
Summary of Intangible Assets	The balance of intangible assets consisted of the following: As of December 31, 2017 2018 RMB RMB Computer software 3,092 3,757 Less: Accumulated amortization (1,540 ) (2,388 ) Intangible assets, net 1,552 1,369
Summary of Amortization Expenses of Intangible Assets	The intangible assets amortization expenses for each of the following fiscal years are as follows: Amortization RMB 2019 717 2020 553 2021 99 Total 1,369

Long-Term Investments (Tables)

Long-Term Investments (Tables)	12 Months Ended
	Dec. 31, 2018
Long Term Investments [Abstract]
Schedule of Long-Term Investments	Long-term investments consisted of the following: As of December 31, 2017 2018 RMB RMB Partnership A (1) 3,300 3,911 Partnership B (2) — 26,098 Total 3,300 30,009 (1) In January 2017, the Group made an investment of RMB8,190 to a limited partnership A (the “Partnership A”) in the PRC, representing 90% of the total investment amount of Partnership A. The Group is the limited partner with no substantive kickout rights, nor substantive participating rights. (2) In August 2018, the Group made an investment of RMB25,000 to a limited partnership B (the “Partnership B”) in the PRC, representing 3.3% of total investment amount of Partnership B. The Group committed to invest another RMB25,000 to this investee upon the request of the general partner of the Partnership B (Note 20).

Other Non-Current Assets (Table

Other Non-Current Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Schedule of Other Non-Current Assets	Other non-current assets consisted of the following: As of December 31, 2017 2018 RMB RMB Rental deposits (1) 9,689 12,772 Prepayment to acquire a building (2) 119,952 404,725 Others — 1,203 Total 129,641 418,700 (1) Rental deposits represent office and enrollment centers’ rental deposits for the Group’s daily operations, which are not refundable within one year. (2) The amounts represent the prepayment for one building (Building D) in Wuhan and the building was under construction by the real estate developer as of December 31, 2018.

Accrued Expenses And Other Li_2

Accrued Expenses And Other Liabilities (Tables)	12 Months Ended
	Dec. 31, 2018
Payables And Accruals [Abstract]
Schedule of Accrued Expenses and Other Liabilities	The components of accrued expenses and other liabilities are as follows: As of December 31, 2017 2018 RMB RMB Salary and welfare payables 148,337 124,137 Accrued marketing expenses 16,133 120,269 Accrued rental expenses 33,693 51,087 Accrued service fees (1) 13,595 94,789 Other tax liabilities 9,915 29,872 Advanced deposits (2) 6,081 6,650 Refund liability (3) 2,452 6,625 Payables for leasehold improvement and intangible assets 2,180 4,911 American Depositary Receipt commission - within one year — 3,482 Payables to educational institutions (4) — 6,024 Payables for share repurchase — 857 Other payables 3,514 6,581 235,900 455,284 (1) The balance represented accrued expenses for outsourced service providers and other professional services. (2 ) Advanced deposits consisted of (1) down payments paid by prospective students before contract signing and (2) insurance (3 ) Refund liability amounted to RMB2,452 and RMB6,625 as of December 31, 2017 and 2018, respectively, representing the estimated amounts of deferred revenue with contingency in cash refund. (4 ) The balances represented tuition fees collected from the students for their registrations with educational institutions.

Revenues and Deferred Revenue (

Revenues and Deferred Revenue (Tables)	12 Months Ended
	Dec. 31, 2018
Disaggregation Of Revenue [Abstract]
Schedule of Disaggregation of Revenue	disaggregated revenues by types and models were as follows: For the years ended December 31, 2016 2017 2018 RMB RMB RMB Disaggregation of revenues Revenue by types: Gross revenues: Degree- or diploma-oriented post-secondary courses 296,269 822,832 1,814,178 Professional certification preparation and professional skills courses 122,005 145,840 161,366 Subtotal Online educational courses 418,274 968,672 1,975,544 Commissions 4,528 4,105 6,374 Others 1,284 1,901 587 Total revenues 424,086 974,678 1,982,505 Less: sales tax and surcharges (5,176 ) (4,516 ) (8,520 ) Total net revenues 418,910 970,162 1,973,985 Revenue by models: Gross revenues: Refundable 79,541 126,277 85,630 Non-refundable 338,733 842,395 1,889,914 Subtotal Online educational courses 418,274 968,672 1,975,544 Commissions 4,528 4,105 6,374 Others 1,284 1,901 587 Total revenues 424,086 974,678 1,982,505 Less: sales tax and surcharges (5,176 ) (4,516 ) (8,520 ) Total net revenues 418,910 970,162 1,973,985
Schedule of Movements of the Deferred Revenue	The movements of the deferred revenue for the years ended December 31, 2017 and 2018 were as follows (1) As of December 31, 2017 2018 RMB RMB Beginning balance (current and noncurrent) 727,569 2,110,428 Additions 2,381,755 3,214,400 Deductions (998,896 ) (2,038,803 ) Ending balance (current and noncurrent) 2,110,428 3,286,025 Deferred revenue, current 1,325,954 1,765,085 Deferred revenue, non-current 784,474 1,520,940 (1) Amounts presented are inclusive of VAT (see VAT in Note 2).

Share Incentive Plan (Tables)

Share Incentive Plan (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Option Activities and Changes	16. SHARE INCENTIVE PLAN - continued Scheme II - continued A summary of option activities and changes during the year ended December 31, 2018 were presented below: Weighted- average Weighted- Weighted- remaining Aggregated average Number of average contractual intrinsic grant date Share option shares exercise price term(years) value fair value RMB RMB RMB Outstanding, December 31, 2017 62,268 560.95 9.81 302 271.90 Forfeited (10,437 ) 560.95 271.90 Outstanding, December 31, 2018 51,831 560.95 8.81 — 271.90
Schedule of Assumptions Used to Calculate Estimated Fair Value of Options	The Company calculated the estimated fair value of the options on the respective grant dates using the binomial option pricing model with the assistance from an independent valuation firm, with the following assumptions used. October 20, Grant Dates 2017 Risk-free interest rate 2.0%-2.4% Volatility 32%-45% Expected dividend yield 0% Exercise multiples 2.2-2.8 Exercise price 0.0312-560.95 Life of option (years) 0.53-10 Fair value of underlying ordinary share 565.80
Schedule of Share-based Compensation Expense Recognized	Total share-based compensation expense of share-based awards granted to employees, certain directors and management recognized for the years ended December 31, 2016, 2017 and 2018 were as follows: For the years ended December 31, 2016 2017 2018 RMB RMB RMB Cost of revenues — 19,244 314 Sales and marketing expenses — 75,237 773 General and administrative expenses — 194,282 2,764 — 288,763 3,851

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Reconciliation of Effective Tax Rate and Statutory Income Tax Rate Applicable to PRC Operations	China - continued The reconciliation of the effective tax rate and the statutory income tax rate applicable to PRC operations is as follows: For the years ended December 31, 2016 2017 2018 RMB RMB RMB Loss before income tax expenses (253,567 ) (913,824 ) (928,660 ) Income tax expenses computed at applicable tax rates of 25% (63,392 ) (228,456 ) (232,165 ) Non-deductible and super deduction expenses 2,477 (3,490 ) (8,013 ) Effect of tax holidays and preferential tax rates 24,808 130,296 64,029 Change in valuation allowance 36,107 101,650 176,149 Income tax expenses — — —
Schedule of Components of Deferred Income Tax	The components of deferred taxes are as follows As of December 31, 2017 2018 RMB RMB Non-current deferred tax assets Accrued expenses 5,108 13,270 Advertising expenses carry-forwards 87,600 87,600 Net operating loss carry-forwards 117,031 285,018 Total non-current deferred tax assets 209,739 385,888 Less: valuation allowance (209,739 ) (385,888 ) Non-current deferred tax assets, net — — Total non-current deferred tax liabilities — —

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Schedule of Calculation of Net Loss Per Share	For the purpose of calculating net loss per share as a result of the 2017 Reorganization as described in Note 1, the number of ordinary shares used in the calculation reflects the outstanding ordinary shares of the Company in 2017 as if the Group’s 2017 Reorganization took place on January 1, 2016: As of December 31, 2016 2017 2018 RMB RMB RMB Numerator: Net loss attributable to Sunlands Technology Group used in basic and diluted net loss per share: Net loss attributable to ordinary shareholders (253,567 ) (918,578 ) (927,022 ) Denominator: Weighted average ordinary shares outstanding used in computing basic and diluted net loss per share 3,818,618 3,945,864 6,294,870 Net loss per share Basic and diluted (66.40 ) (232.80 ) (147.27 )

Amounts Due From_To Related P_2

Amounts Due From/To Related Parties (Tables)	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Schedule of Major Related Parties and Their Relationships with Group	(1) The table below sets forth the major related parties and their relationship with the Group. Name of related parties Relationship with the Group Shangde Jiaxun Entity controlled by the Founder and the CEO (Note 1) ELITE CONCEPT HOLDINGS LIMITED Class A Ordinary Shares holder Shanghai Chuang Ji Investment Center (Limited Partnership) (“Shanghai Chuang Ji”) Class A Ordinary Shares holder Shenzhen Xingwang Hulian II Investment Center (Limited Partnership) (“Shenzhen Xingwang”) Class A Ordinary Shares holder
Summary of Related Party Transactions	(2) The related party transactions were as follows: For the years ended December 31, 2016 2017 2018 RMB RMB RMB Disposal of a subsidiary to a related party — 1,000 —
Schedule of Amounts Due from Related Parties	(3) As of December 31, 2017 and 2018, the aggregate amounts due from related parties were set forth below: As of December 31, 2017 2018 RMB RMB Shangde Jiaxun (i) 8,018 — ELITE CONCEPT HOLDINGS LIMITED (ii) 162,000 — Shanghai Chuang Ji (ii) 80,000 — Shenzhen Xingwang (ii) 78 — 250,096 — (i) The balances as of December 31, 2017 included the consideration receivable of RMB1,000 from disposal of a subsidiary. The remaining balance of RMB7,018 were interest-free, unsecured and repayable on demand. The balance as of December 31, 2017 was fully repaid in February 2018. (ii) The balances as of December 31, 2017 represented the original investments of RMB242,078 in Series A Equity Interest withdrew from Beijing Sunlands by certain Series A Preferred Shareholders which were reinvested in full to the Company in January 2018 (Note 13). (4) As of December 31, 2017 and 2018, the aggregate amounts due to related parties were both nil.

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Minimum Payments Under Non-Cancelable Operating Leases to Offices and Public Displays With Initial Terms of One-Year or Longer	Future minimum payments under non-cancelable operating leases related to offices and public displays with initial terms of one-year or longer consisted of the following at December 31, 2018: RMB 2019 110,796 2020 97,949 2021 90,347 2022 83,251 2023 and thereafter 698,995 1,081,338

Organization and Basis of Pre_3

Organization and Basis of Presentation - Additional Information (Details) - CNY (¥) ¥ in Thousands	5 Months Ended
	Jul. 31, 2016	Dec. 31, 2018	Dec. 31, 2015	Mar. 31, 2012
Variable Interest Entity [Line Items]
Recognized reorganization value			¥ 49,359
Sale or purchase of assets or rights minimum amount		¥ 50
Option agreement maximum contract amount		50
Consolidated VIE assets		0
Consolidated VIE creditor		¥ 0
Beijing Shangzhi Jiaye Education Technology Co., Ltd
Variable Interest Entity [Line Items]
Percentage of voting equity interests acquired	100.00%
Cash consideration	¥ 293,644
Sunland Education Technology H K Limited
Variable Interest Entity [Line Items]
Ownership percentage by parent				100.00%
Wuhan Zhibo
Variable Interest Entity [Line Items]
Ownership percentage by parent		100.00%
Wuhan Zhibo | Minimum
Variable Interest Entity [Line Items]
Ownership percentage by parent		10.00%
Wuhan Zhibo | Maximum
Variable Interest Entity [Line Items]
Ownership percentage by parent		100.00%

Organization and Basis of Pre_4

Organization and Basis of Presentation - Summary of Subsidiaries VIEs and VIEs' Subsidiaries (Details)	12 Months Ended
	Dec. 31, 2018
Sunlands HK
Variable Interest Entity [Line Items]
Date of establishment/ acquisition	Oct. 6, 2015
Place of establishment	HongKong
Percentage of direct or indirect economic ownership	100.00%
Principal activities	Investment holding
Wuhan Zhibo
Variable Interest Entity [Line Items]
Date of establishment/ acquisition	Aug. 2, 2017
Place of establishment	PRC
Percentage of direct or indirect economic ownership	100.00%
Principal activities	Provision of technical consultation and services
Beijing Sunlands
Variable Interest Entity [Line Items]
Date of establishment/ acquisition	Sep. 27, 2013
Place of establishment	PRC
Principal activities	Investment holding and provision of education services
Tianjin Sunlands
Variable Interest Entity [Line Items]
Date of establishment/ acquisition	Jul. 31, 2017
Place of establishment	PRC
Percentage of direct or indirect economic ownership	100.00%
Principal activities	Provision of technical consultation and services
Tianjin Shangde
Variable Interest Entity [Line Items]
Date of establishment/ acquisition	Mar. 21, 2018
Place of establishment	PRC
Principal activities	Provision of education services
Beijing Shangzhi Jiaye Education Technology Co., Ltd
Variable Interest Entity [Line Items]
Date of establishment/ acquisition	Mar. 13, 2012
Place of establishment	PRC
Percentage of direct or indirect economic ownership	100.00%
Principal activities	Provision of education services
Beijing Shangren Chongye Education Technology Co., Ltd.
Variable Interest Entity [Line Items]
Date of establishment/ acquisition	Sep. 27, 2013
Place of establishment	PRC
Percentage of direct or indirect economic ownership	100.00%
Principal activities	Provision of education services
Guangdong Shangde Online Education Technology Co., Ltd.
Variable Interest Entity [Line Items]
Date of establishment/ acquisition	Oct. 15, 2013
Place of establishment	PRC
Percentage of direct or indirect economic ownership	100.00%
Principal activities	Provision of education services
Urumchi Shangde Renye Business Consulting Co., Ltd.
Variable Interest Entity [Line Items]
Date of establishment/ acquisition	Mar. 10, 2015
Place of establishment	PRC
Percentage of direct or indirect economic ownership	100.00%
Principal activities	Provision of education services
Guangzhou Youhe Self-study Training School
Variable Interest Entity [Line Items]
Date of establishment/ acquisition	May 19, 2015
Place of establishment	PRC
Percentage of direct or indirect economic ownership	100.00%
Principal activities	Provision of education services
Beijing Bainiao Education Technology Co., Ltd.
Variable Interest Entity [Line Items]
Date of establishment/ acquisition	Mar. 3, 2016
Place of establishment	PRC
Percentage of direct or indirect economic ownership	100.00%
Principal activities	Provision of education services
Shanghai Shangchi Education Technology Co., Ltd.
Variable Interest Entity [Line Items]
Date of establishment/ acquisition	Dec. 22, 2016
Place of establishment	PRC
Percentage of direct or indirect economic ownership	90.00%
Principal activities	Provision of education services
Beijing Shangren Side Education Technology Co., Ltd.
Variable Interest Entity [Line Items]
Date of establishment/ acquisition	Jun. 2, 2017
Place of establishment	PRC
Percentage of direct or indirect economic ownership	100.00%
Principal activities	Provision of education services
Shanghai Shangchi Institute
Variable Interest Entity [Line Items]
Date of establishment/ acquisition	Sep. 1, 2017
Place of establishment	PRC
Percentage of direct or indirect economic ownership	100.00%
Principal activities	Provision of education services
Guangzhou Shangzhi Side Education Technology Co., Ltd.
Variable Interest Entity [Line Items]
Date of establishment/ acquisition	Sep. 28, 2017
Place of establishment	PRC
Percentage of direct or indirect economic ownership	100.00%
Principal activities	Provision of education services

Organization and Basis of Pre_5

Organization and Basis of Presentation - Summary Financial Information of VIEs and their Subsidiaries (Details) - CNY (¥) ¥ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Total current assets	¥ 818,480	¥ 507,410
Total assets	1,196,336	954,006
Total current liabilities	2,006,289	1,729,642
Total liabilities	3,527,364	2,514,116
Net revenues	1,973,985	970,162	¥ 418,910
Net (loss)/income	393,063	(606,946)	(253,563)
Net cash generated from operating activities	1,448,005	845,616	89,272
Net cash used in investing activities	(315,198)	(375,802)	(117,695)
Net cash generated from (used in) financing activities	8,018	(391,237)	¥ 47,080
Prepaid Expenses and Other Current Assets
Variable Interest Entity [Line Items]
Total current assets	46,601	38,813
Accrued Expenses and Other Current Liabilities
Variable Interest Entity [Line Items]
Total current liabilities	241,204	223,298
Deferred Revenue Current
Variable Interest Entity [Line Items]
Total current liabilities	1,765,085	1,325,954
Payables to Acquire Buildings
Variable Interest Entity [Line Items]
Total current liabilities		180,390
Deferred Revenue Non-Current
Variable Interest Entity [Line Items]
Non-current liabilities	1,520,940	784,474
Other Non-Current Liabilities
Variable Interest Entity [Line Items]
Non-current liabilities	135
Cash and Cash Equivalents
Variable Interest Entity [Line Items]
Total current assets	80,371	101,680
Short-term Investments
Variable Interest Entity [Line Items]
Total current assets	¥ 587,051	¥ 309,070

Significant Accounting Polici_4

Significant Accounting Policies - Additional Information (Details) ¥ in Thousands	May 01, 2016	Apr. 30, 2016	Dec. 31, 2018CNY (¥)PerformanceObligationCustomer$ / ¥	Dec. 31, 2017CNY (¥)	Dec. 31, 2016CNY (¥)
Significant Accounting Policies [Line Items]
Currency exchange rate, Renminbi ("RMB") to U.S. dollar | $ / ¥			6.8755
Advertising expenses			¥ 983,012	¥ 499,294	¥ 188,516
Cash and cash equivalents available for conversion to foreign currency			¥ 157,103	¥ 104,244
Percentage of cash and cash equivalents available for conversion to foreign currency			12.60%	18.60%
Total Net Revenues | Customer Concentration Risk
Significant Accounting Policies [Line Items]
Number of Customers | Customer			0
Revenues from customers individually representing portion of total net revenues			10.00%
Other Income [Member]
Significant Accounting Policies [Line Items]
Government subsidies			¥ 28,688	¥ 3,223	¥ 1,601
Maximum
Significant Accounting Policies [Line Items]
Time for full refund of transaction price			24 hours
Time for partial refund of transaction price			7 days
Term of repayment of principal installments on which interest expense and service fees payable			12 months
Minimum
Significant Accounting Policies [Line Items]
Term of repayment of principal installments on which interest expense and service fees payable			3 months
Degree- or Diploma-oriented Post-secondary Courses
Significant Accounting Policies [Line Items]
Weighted average service period			31 months
Professional Certification Preparation and Professional Skills Courses
Significant Accounting Policies [Line Items]
Weighted average service period			20 months
Online Education Service and Insurance Service [Member]
Significant Accounting Policies [Line Items]
Number of performance obligation | PerformanceObligation			2
Educational Services
Significant Accounting Policies [Line Items]
Rate of business tax and related surcharges		3.36%
Rate of VAT	3.00%
Educational Services | Tianjin Shangde
Significant Accounting Policies [Line Items]
Rate of VAT	6.00%
Non-educational Services
Significant Accounting Policies [Line Items]
Rate of business tax and related surcharges		5.60%
Rate of VAT	6.00%

Significant Accounting Polici_5

Significant Accounting Policies - Summary of Estimated Useful Lives of Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2018
Buildings | Minimum
Property Plant And Equipment [Line Items]
Estimated useful life	36 years
Buildings | Maximum
Property Plant And Equipment [Line Items]
Estimated useful life	37 years
Leasehold and Buildings Improvements
Property Plant And Equipment [Line Items]
Estimated useful life	Shorter of lease term or expected useful life
Electronic and Office Equipment | Minimum
Property Plant And Equipment [Line Items]
Estimated useful life	3 years
Electronic and Office Equipment | Maximum
Property Plant And Equipment [Line Items]
Estimated useful life	5 years

Significant Accounting Polici_6

Significant Accounting Policies - Summary of Estimated Useful Lives of Intangible Assets (Details)	12 Months Ended
	Dec. 31, 2018
Computer Software
Finite Lived Intangible Assets [Line Items]
Estimated useful life	3 years

Short-Term Investments - Schedu

Short-Term Investments - Schedule of Short-Term Investment (Details) ¥ in Thousands, $ in Thousands	Dec. 31, 2018CNY (¥)	Dec. 31, 2018USD ($)	Dec. 31, 2017CNY (¥)
Investments Debt And Equity Securities [Abstract]
Short-term investments	¥ 1,028,564	$ 149,598	¥ 353,070

Short-Term Investments - Additi

Short-Term Investments - Additional Information (Details) - CNY (¥)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Investments Debt And Equity Securities [Abstract]
Impairment loss on short-term investments	¥ 0	¥ 0	¥ 0

Prepaid Expenses and Other Cu_3

Prepaid Expenses and Other Current Assets - Summary of Prepaid Expenses and Other Current Assets (Details) ¥ in Thousands, $ in Thousands		Dec. 31, 2018CNY (¥)	Dec. 31, 2018USD ($)	Dec. 31, 2017CNY (¥)
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Prepaid and input VAT		¥ 58,234		¥ 14,440
Prepaid marketing expenses		23,756		9,059
Interest receivables	[1]	11,632
Prepaid expenses	[2]	10,820		10,081
Deferred IPO expenses				5,746
Deposits	[3]	4,595		5,154
Receivables from third-party payment platforms		3,886		3,045
Staff advances		9,242		932
Others		2,743		536
Total		¥ 124,908	$ 18,169	¥ 48,993
[1]	Represented interest receivables from short-term investments (Note 3).
[2]	Represented the prepaid expenses for telecommunications, network, service for online live steaming, advertising and rental.
[3]	Represented rental deposits, deposits for search engine marketing activities and deposits for leasehold improvement of buildings which all being refundable within one year.

Deferred Costs - Schedule of Mo

Deferred Costs - Schedule of Movements of Deferred Costs (Details) ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018CNY (¥)	Dec. 31, 2017CNY (¥)	Dec. 31, 2018USD ($)
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Beginning balances (current and non-current)	¥ 98,260	¥ 25,228
Additions	374,594	121,327
Amortizations	(145,488)	(48,213)
Impairments	(99)	(82)
Ending balances (current and non-current)	327,267	98,260
Deferred costs, current	180,657	55,073	$ 26,275
Deferred costs, non-current	¥ 146,610	¥ 43,187	$ 21,324

Property and Equipment, Net - S

Property and Equipment, Net - Summary of Property and Equipment Consisted (Details) ¥ in Thousands, $ in Thousands		Dec. 31, 2018CNY (¥)	Dec. 31, 2018USD ($)	Dec. 31, 2017CNY (¥)
Property Plant And Equipment [Line Items]
Total cost		¥ 601,472		¥ 542,324
Less: Accumulated depreciation		(41,961)		(17,036)
Property and equipment, net		559,511	$ 81,377	525,288
Leasehold and Buildings Improvements
Property Plant And Equipment [Line Items]
Total cost		91,265		40,675
Electronic and Office Equipment
Property Plant And Equipment [Line Items]
Total cost		29,936		16,061
Buildings
Property Plant And Equipment [Line Items]
Total cost	[1]	¥ 480,271		¥ 485,588
[1]	In 2017, the Group purchased two buildings in Wuhan (Building A and B) and one building in Guangzhou (Building C) with a total consideration of RMB480,271. RMB60,000 of the consideration was paid by a mortgage loan provided by a PRC bank in August 2018 (Note 12).

Property and Equipment, Net -_2

Property and Equipment, Net - Summary of Property and Equipment Consisted (Parenthetical) (Details) ¥ in Thousands	1 Months Ended	12 Months Ended
	Aug. 31, 2018CNY (¥)	Dec. 31, 2017CNY (¥)Building
Mortgage Loan
Business Acquisition [Line Items]
Consideration paid to acquire buildings | ¥	¥ 60,000
Buildings
Business Acquisition [Line Items]
Buildings purchased under consideration | ¥		¥ 480,271
Wuhan
Business Acquisition [Line Items]
Number of buildings purchased | Building		2
Guangzhou
Business Acquisition [Line Items]
Number of buildings purchased | Building		1

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - CNY (¥) ¥ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Abstract]
Depreciation expenses	¥ 24,930	¥ 7,333	¥ 4,993

Intangible Assets, Net - Summar

Intangible Assets, Net - Summary of Intangible Assets (Details) ¥ in Thousands, $ in Thousands	Dec. 31, 2018CNY (¥)	Dec. 31, 2018USD ($)	Dec. 31, 2017CNY (¥)
Finite Lived Intangible Assets [Line Items]
Less: Accumulated amortization	¥ (2,388)		¥ (1,540)
Intangible assets, net	1,369	$ 199	1,552
Computer Software
Finite Lived Intangible Assets [Line Items]
Intangible assets, gross	¥ 3,757		¥ 3,092

Intangible Assets, Net - Additi

Intangible Assets, Net - Additional Information (Details) - CNY (¥) ¥ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill And Intangible Assets Disclosure [Abstract]
Amortization expenses	¥ 848	¥ 776	¥ 477

Intangible Assets, Net - Summ_2

Intangible Assets, Net - Summary of Amortization Expenses of Intangible Assets (Details) ¥ in Thousands, $ in Thousands	Dec. 31, 2018CNY (¥)	Dec. 31, 2018USD ($)	Dec. 31, 2017CNY (¥)
Goodwill And Intangible Assets Disclosure [Abstract]
2019	¥ 717
2020	553
2021	99
Intangible assets, net	¥ 1,369	$ 199	¥ 1,552

Long-Term Investments - Schedul

Long-Term Investments - Schedule of Long-Term Investments (Details) ¥ in Thousands, $ in Thousands	Dec. 31, 2018CNY (¥)	Dec. 31, 2018USD ($)	Dec. 31, 2017CNY (¥)
Investment [Line Items]
Long-term investments	¥ 30,009	$ 4,365	¥ 3,300
Partnership A
Investment [Line Items]
Long-term investments	3,911		¥ 3,300
Partnership B
Investment [Line Items]
Long-term investments	¥ 26,098

Long-Term Investments - Sched_2

Long-Term Investments - Schedule of Long-Term Investments (Parenthetical) (Details) ¥ in Thousands, $ in Thousands	1 Months Ended		12 Months Ended
	Aug. 31, 2018CNY (¥)	Jan. 31, 2017CNY (¥)	Dec. 31, 2018CNY (¥)	Dec. 31, 2018USD ($)	Dec. 31, 2017CNY (¥)
Schedule Of Equity Method Investments [Line Items]
Investment paid			¥ 25,000	$ 3,636	¥ 8,190
Long-term Investments
Schedule Of Equity Method Investments [Line Items]
Investment commitment amount			¥ 25,000
Partnership A
Schedule Of Equity Method Investments [Line Items]
Investment paid		¥ 8,190
Percentage of total investment amount		90.00%
Partnership B
Schedule Of Equity Method Investments [Line Items]
Investment paid	¥ 25,000
Percentage of total investment amount	3.30%
Partnership B | Long-term Investments
Schedule Of Equity Method Investments [Line Items]
Investment commitment amount	¥ 25,000

Long-Term Investments - Additio

Long-Term Investments - Additional Information (Details) - CNY (¥)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Equity Method Investments And Joint Ventures [Abstract]
Impairment loss	¥ 0	¥ 0

Other Non-Current Assets - Summ

Other Non-Current Assets - Summary of Other Non-Current Assets (Details) ¥ in Thousands, $ in Thousands		Dec. 31, 2018CNY (¥)	Dec. 31, 2018USD ($)	Dec. 31, 2017CNY (¥)
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Rental deposits	[1]	¥ 12,772		¥ 9,689
Prepayment to acquire a building	[2]	404,725		119,952
Others		1,203
Total		¥ 418,700	$ 60,897	¥ 129,641
[1]	Rental deposits represent office and enrollment centers’ rental deposits for the Group’s daily operations, which are not refundable within one year.
[2]	The amounts represent the prepayment for one building (Building D) in Wuhan and the building was under construction by the real estate developer as of December 31, 2018

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Liabilities (Details) ¥ in Thousands, $ in Thousands	Dec. 31, 2018CNY (¥)	Dec. 31, 2018USD ($)	Dec. 31, 2017CNY (¥)
Payables And Accruals [Abstract]
Salary and welfare payables	¥ 124,137		¥ 148,337
Accrued marketing expenses	120,269		16,133
Accrued rental expenses	51,087		33,693
Accrued service fees	94,789		13,595
Other tax liabilities	29,872		9,915
Advanced deposits	6,650		6,081
Refund liability	6,625		2,452
Payables for leasehold improvement and intangible assets	4,911		2,180
American Depositary Receipt commission - within one year	3,482
Payables to educational institutions	6,024
Payables for share repurchase	857
Other payables	6,581		3,514
Total	¥ 455,284	$ 66,218	¥ 235,900

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Liabilities (Parenthetical) (Details) - CNY (¥) ¥ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Refund liability	¥ 6,625	¥ 2,452

Revenues and Deferred Revenue -

Revenues and Deferred Revenue - Schedule of Disaggregated Revenues (Details) ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018CNY (¥)	Dec. 31, 2018USD ($)	Dec. 31, 2017CNY (¥)	Dec. 31, 2016CNY (¥)
Disaggregation Of Revenue [Line Items]
Total revenues	¥ 1,982,505		¥ 974,678	¥ 424,086
Less: sales tax and surcharges	(8,520)		(4,516)	(5,176)
Total net revenues	1,973,985	$ 287,104	970,162	418,910
Subtotal Online Educational Courses
Disaggregation Of Revenue [Line Items]
Total revenues	1,975,544		968,672	418,274
Degree- or Diploma-oriented Post-secondary Courses | Subtotal Online Educational Courses
Disaggregation Of Revenue [Line Items]
Total revenues	1,814,178		822,832	296,269
Professional Certification Preparation and Professional Skills Courses | Subtotal Online Educational Courses
Disaggregation Of Revenue [Line Items]
Total revenues	161,366		145,840	122,005
Commissions
Disaggregation Of Revenue [Line Items]
Total revenues	6,374		4,105	4,528
Other Revenue
Disaggregation Of Revenue [Line Items]
Total revenues	587		1,901	1,284
Refundable | Subtotal Online Educational Courses
Disaggregation Of Revenue [Line Items]
Total revenues	85,630		126,277	79,541
Non-refundable | Subtotal Online Educational Courses
Disaggregation Of Revenue [Line Items]
Total revenues	¥ 1,889,914		¥ 842,395	¥ 338,733

Revenues and Deferred Revenue_2

Revenues and Deferred Revenue - Schedule of Movement of the Deferred Revenue (Details) ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018CNY (¥)	Dec. 31, 2017CNY (¥)	Dec. 31, 2018USD ($)
Disaggregation Of Revenue [Abstract]
Beginning balance (current and noncurrent)	¥ 2,110,428	¥ 727,569
Additions	3,214,400	2,381,755
Deductions	(2,038,803)	(998,896)
Ending balance (current and noncurrent)	3,286,025	2,110,428
Deferred revenue, current	1,765,085	1,325,954	$ 256,721
Deferred revenue, non-current	¥ 1,520,940	¥ 784,474	$ 221,212

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Details) - Mortgage Loan - PRC Bank ¥ in Thousands	12 Months Ended
	Dec. 31, 2018	Nov. 21, 2018CNY (¥)Loan	Aug. 29, 2018CNY (¥)Loan
Debt Instrument [Line Items]
Debt instrument number of loan agreement | Loan		2	2
Debt instrument, face amount | ¥		¥ 260,000	¥ 260,000
Debt instrument periodic payment description	The loans are secured by pledging the Building A and Building D and are repaid in equal instalment every three months
Debt instrument, interest rate	5.782%
Debt instrument, term	8 years

Convertible Redeemable Prefer_2

Convertible Redeemable Preferred Share - Additional Information (Details) ¥ in Thousands	Sep. 01, 2017	Aug. 15, 2017	Jul. 05, 2016CNY (¥)	Nov. 30, 2017CNY (¥)	Sep. 30, 2017CNY (¥)shares	Sep. 30, 2017USD ($)shares	Aug. 31, 2017CNY (¥)shares	Aug. 31, 2017USD ($)shares	Dec. 31, 2018USD ($)	Dec. 31, 2017CNY (¥)	Mar. 31, 2018shares
Temporary Equity [Line Items]
Proceeds from issuance of temporary equity | ¥										¥ 732,709
Minimum
Temporary Equity [Line Items]
Percentage of fully diluted capital stock									10.00%
Convertible redeemable preferred share conversion of market capitalization | $									$ 500,000,000
Aggregate gross proceeds | $									$ 100,000,000
Series B Convertible Redeemable Preferred Shares
Temporary Equity [Line Items]
Proceeds from issuance of temporary equity							¥ 601,605	$ 90,000,000
Temporary stock shares issued							826,389	826,389
Preferred stock outstanding											826,389
Convertible redeemable preferred shares converted into ordinary share											826,389
Series B+ Convertible Redeemable Preferred Shares
Temporary Equity [Line Items]
Proceeds from issuance of temporary equity					¥ 131,104	$ 20,000,000
Temporary stock shares issued					141,264	141,264
Preferred stock outstanding											141,264
Convertible redeemable preferred shares converted into ordinary share											141,264
Series A Convertible Redeemable Preferred Shares
Temporary Equity [Line Items]
Temporary equity shares redeemed | ¥							¥ 86,000
Temporary stock shares issued							954,274	954,274
Proceeds from withdrawal of original investment | ¥				¥ 242,078
Preferred stock outstanding											954,274
Convertible redeemable preferred shares converted into ordinary share											954,274
Series A Preferred Shares
Temporary Equity [Line Items]
Debt instrument redemption description									In the event that the Company has not consummated a Series A Target IPO as of the date that is thirty months after August 15, 2017 (or such other later date as approved at any time by the holders of not less than three fourths of the then issued and outstanding Series A Preferred Shares), each Series A Preferred Shareholder shall have the option, but is not required to sell all or a portion of the Series A Preferred Shares held at a price of the original issuance price plus a simple rate of 10% interest per annum since the date of issuance to the date on which the applicable redemption amount is paid in full.
Simple interest rate per annum		10.00%
Preferred stock, redemption value | ¥										303,040
Compound interest rate per annum									10.00%
Series B Preferred Shares
Temporary Equity [Line Items]
Debt instrument redemption description									In the event that the Company has not consummated a Qualified IPO as of the fifth anniversary of August 15, 2017, or has consummated an initial public offering that is not a Qualified IPO at any time prior to the fifth anniversary of August 15, 2017, each Series B Preferred Shareholder shall have the option, but is not required to sell all or a portion of the Series B Preferred Shares held at a price of the original issuance price plus a compound rate of 10% interest per annum since the date of issuance to the date on which the applicable redemption amount is paid in full.
Preferred stock, redemption value | ¥										623,679
Compound interest rate per annum		10.00%
Series B+ Preferred Shares
Temporary Equity [Line Items]
Debt instrument redemption description									In the event that the Company has not consummated a Qualified IPO as of the fifth anniversary of September 1, 2017, or has consummated an initial public offering that is not a Qualified IPO at any time prior to the fifth anniversary of September 1, 2017, each Series B+ Preferred Shareholder shall have the option, but is not required to sell all or a portion of the Series B+ Preferred Shares held at a price of the original issuance price plus a compound rate of 10% interest per annum since the date of issuance to the date on which the applicable redemption amount is paid in full.
Preferred stock, redemption value | ¥										¥ 135,312
Compound interest rate per annum	10.00%
Series B and B+ Preferred Shares
Temporary Equity [Line Items]
Compound interest rate per annum									8.00%
Beijing Sunlands | Series A Convertible Redeemable Preferred Shares
Temporary Equity [Line Items]
Percentage of temporary stock shares issued			20.27%
Proceeds from issuance of temporary equity | ¥			¥ 335,000

Ordinary Shares - Additional In

Ordinary Shares - Additional Information (Details) ¥ / shares in Units, $ / shares in Units, ¥ in Thousands	1 Months Ended			12 Months Ended
	Mar. 31, 2018CNY (¥)Voteshares	Oct. 31, 2017	Aug. 31, 2017shares	Dec. 31, 2018CNY (¥)shares	Dec. 31, 2018USD ($)shares	Dec. 31, 2017CNY (¥)	Dec. 31, 2018$ / shares	Aug. 29, 2018USD ($)	Dec. 31, 2017$ / sharesshares	Dec. 31, 2016shares	Dec. 31, 2015shares	Sep. 18, 2015$ / sharesshares	Sep. 18, 2015¥ / sharesshares
Ordinary Shares [Line Items]
Ordinary shares, shares authorized				1,000,000,000					1,000,000,000			1,000,000,000	1,000,000,000
Ordinary shares, par value | (per share)							$ 0.00005		$ 0.00005			$ 0.00005	¥ 0.0003
Ordinary shares, shares issued									4,329,000			1	1
Share split, description				The shareholders of the Company approved a share split at a 1 to 2 ratio for each ordinary share and Preferred Share.	The shareholders of the Company approved a share split at a 1 to 2 ratio for each ordinary share and Preferred Share.
Share split, conversion ratio		0.5
Proceeds from initial public offering, net of issuance cost of 80,128	¥ 1,109,517			¥ 1,109,517	$ 161,373,000
Stock issuance costs | ¥	¥ 80,128			¥ 80,128		¥ 80,128
Ordinary shares, shares outstanding	4,329,000								4,329,000
American Depository Shares
Ordinary Shares [Line Items]
Ordinary shares newly issued	16,478,275
Number of shares repurchased				1,127,055	1,127,055
Class A Ordinary Shares
Ordinary Shares [Line Items]
Ordinary shares, shares authorized				796,062,195					796,062,195
Ordinary shares, par value | $ / shares							0.00005		$ 0.00005
Ordinary shares, shares issued				1,818,383
Ordinary shares newly issued	659,131			659,131	659,131
Common stock, voting right				Class A ordinary share is entitled to one vote	Class A ordinary share is entitled to one vote
Number of vote each ordinary shares entitled | Vote	1
Ordinary shares, shares outstanding	63,714			1,773,301
Authorized amount under share repurchase program | $								$ 50,000
Number of shares repurchased				45,082	45,082
Stock Repurchased During Period, Value | ¥				¥ 34,828
Class B Ordinary Shares
Ordinary Shares [Line Items]
Ordinary shares, shares authorized				826,389					826,389
Ordinary shares, par value | $ / shares							0.00005		$ 0.00005
Ordinary shares, shares issued				826,389
Common stock, voting right				Class B ordinary share is entitled to seven votes	Class B ordinary share is entitled to seven votes
Number of vote each ordinary shares entitled | Vote	7
Class of each ordinary shares convertible into class A ordinary shares	1
Ordinary shares, shares outstanding				826,389
Class C Ordinary Shares
Ordinary Shares [Line Items]
Ordinary shares, shares authorized				203,111,416					203,111,416
Ordinary shares, par value | $ / shares							$ 0.00005		$ 0.00005
Ordinary shares, shares issued				4,265,286
Common stock, voting right				Class C ordinary share is entitled to ten votes	Class C ordinary share is entitled to ten votes
Number of vote each ordinary shares entitled | Vote	10
Class of each ordinary shares convertible into class A ordinary shares	1
Ordinary shares, shares outstanding	4,265,286			4,265,286
Additional Ordinary Shares
Ordinary Shares [Line Items]
Ordinary shares, shares outstanding									4,329,000	3,818,618	3,818,618
Additional Ordinary Shares | Directors and Management
Ordinary Shares [Line Items]
Ordinary shares issued for no consideration			146,930
2017 Reorganization | Additional Ordinary Shares
Ordinary Shares [Line Items]
Ordinary shares newly issued			1,909,309

Share Incentive Plan - Addition

Share Incentive Plan - Additional Information (Details)	Oct. 20, 2017$ / sharesshares	Oct. 20, 2017$ / shares¥ / sharesshares	Apr. 26, 2019CNY (¥)	Aug. 31, 2017CNY (¥)shares	Dec. 31, 2018CNY (¥)	Dec. 31, 2017CNY (¥)shares	Aug. 24, 2018shares	Oct. 31, 2017shares	Oct. 20, 2017¥ / shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Allocated Share-based Compensation Expense | ¥					¥ 3,851,000	¥ 288,763,000
Dividend payout ratio assumed					0.00%
Unrecognized share-based compensation expenses | ¥					¥ 14,083,000
Weighted average recognition period of unrecognized share-based compensation expenses					3 years 2 months 12 days
Directors and Management
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based compensation expense | ¥				¥ 83,133,000
Additional Ordinary Shares | Directors and Management
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Ordinary shares issued for no consideration | shares				146,930
Additional Ordinary Shares | Independent Directors | Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares issued in exchange for services | ¥			¥ 1,100,000
2017 Share Incentive Plan | Additional Ordinary Shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares approved for grant | shares							345,503	483,846
Common Stock, Capital Shares Reserved for Future Issuance | shares							829,349
Scheme I
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted | shares	363,452	363,452
Exercise price | (per share)	$ 0.0047	$ 0.0047							¥ 0.0312
Number of shares exercised | shares						363,452
Allocated Share-based Compensation Expense | ¥						¥ 205,630,000
Scheme II
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares granted | shares	66,053	66,053
Allocated Share-based Compensation Expense | ¥					¥ 2,751,000	¥ 0
Exercise price | (per share)	$ 84.75	$ 560.95
Scheme II | Vested on First Anniversary Grand Date
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options vesting percentage					10.00%
Scheme II | Vested on Over Next Three Years
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options vesting percentage					20.00%
Scheme II | Vested on Third Anniversary of Company IPO
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options vesting percentage					30.00%
Scheme II | Vested on Fourth Anniversary of Company IPO
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options vesting percentage					40.00%

Share Incentive Plan - Summary

Share Incentive Plan - Summary of Option Activities and Changes (Details) - Employee Stock Option - CNY (¥) ¥ / shares in Units, ¥ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares, Outstanding beginning balance	62,268
Number of shares, Forfeited	(10,437)
Number of shares, Outstanding ending balance	51,831	62,268
Weighted-average exercise price, Outstanding beginning balance	¥ 560.95
Weighted-average exercise price, Forfeited	560.95
Weighted-average exercise price, Outstanding ending balance	¥ 560.95	¥ 560.95
Weighted-average remaining contractual term, Outstanding	8 years 9 months 21 days	9 years 9 months 21 days
Aggregated intrinsic value, Outstanding beginning balance	¥ 302
Aggregated intrinsic value, Outstanding ending balance		¥ 302
Weighted average grant date fair value, Outstanding beginning balance	¥ 271.90
Weighted average grant date fair value, Forfeited	271.90
Weighted average grant date fair value, Outstanding ending balance	¥ 271.90	¥ 271.90

Share Incentive Plan - Schedule

Share Incentive Plan - Schedule of Assumptions Used to Calculate Estimated Fair Value of Options (Details) - Binomial Option Pricing Model	Oct. 20, 2017¥ / shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate, minimum	2.00%
Risk-free interest rate, maximum	2.40%
Volatility, minimum	32.00%
Volatility, maximum	45.00%
Expected dividend yield	0.00%
Fair value of underlying ordinary share	¥ 565.80
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise multiples	2.2
Exercise price	¥ 0.0312
Life of option (years)	6 months 10 days
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise multiples	2.8
Exercise price	¥ 560.95
Life of option (years)	10 years

Share Incentive Plan - Schedu_2

Share Incentive Plan - Schedule of Share-based Compensation Expense Recognized (Details) - CNY (¥) ¥ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	¥ 3,851	¥ 288,763
Cost of Revenues
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	314	19,244	¥ 0
Selling and Marketing Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	773	75,237	0
General and Administrative Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	¥ 2,764	¥ 194,282	¥ 0

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018CNY (¥)	Dec. 31, 2018USD ($)	Dec. 31, 2017CNY (¥)	Dec. 31, 2016CNY (¥)
Income Taxes [Line Items]
Statutory income tax rate	25.00%	25.00%	25.00%	25.00%
Income tax expenses	¥ 0	$ 0	¥ 0	¥ 0
Income tax expenses if the tax holidays granted to Beijing Sunlands and Previous WFOE were not available	0
Uncertain tax positions	¥ 0		0	0
Income tax rate outside the PRC	25.00%	25.00%
Hong Kong
Income Taxes [Line Items]
Income tax expenses	¥ 0		¥ 0	¥ 0
Hong Kong | For the First 2 Million Profits
Income Taxes [Line Items]
Statutory income tax rate	8.25%	8.25%
Hong Kong | For the Remaining Profits
Income Taxes [Line Items]
Statutory income tax rate	16.50%	16.50%
China
Income Taxes [Line Items]
Statutory income tax rate	25.00%	25.00%
Deferred income tax expense	¥ 0
China | subsidiaries and the Variable Interest Entities
Income Taxes [Line Items]
Statutory income tax rate	25.00%	25.00%
Operating loss carryforwards	¥ 1,677,243
Expiration start date	Dec. 31, 2019	Dec. 31, 2019
Expiration end date	Dec. 31, 2028	Dec. 31, 2028
China | 2015 | Beijing Shangzhi Jiaye Education Technology Co., Ltd
Income Taxes [Line Items]
Preferential income tax rate description	From 2015, Previous WFOE qualified as “high and new technology enterprise strongly supported by the State” (“HNTE”) under the EIT Law, and therefore, was entitled to preferential income tax rate of 15% from 2015 through 2017.	From 2015, Previous WFOE qualified as “high and new technology enterprise strongly supported by the State” (“HNTE”) under the EIT Law, and therefore, was entitled to preferential income tax rate of 15% from 2015 through 2017.
Preferential income tax rate	15.00%	15.00%
Preferential income tax exemption approved start year	2015	2015
Preferential income tax exemption approved end year	2017	2017
China | 2016 | Beijing Sunlands
Income Taxes [Line Items]
Preferential income tax rate description	In 2016, Beijing Sunlands obtained HNTE qualification and was entitled to preferential income tax rate of 15% from 2016 through 2018.	In 2016, Beijing Sunlands obtained HNTE qualification and was entitled to preferential income tax rate of 15% from 2016 through 2018.
Preferential income tax rate	15.00%	15.00%
Preferential income tax exemption approved start year	2016	2016
Preferential income tax exemption approved end year	2018	2018

Income Taxes - Schedule of Reco

Income Taxes - Schedule of Reconciliation of Effective Tax Rate and Statutory Income Tax Rate Applicable to PRC Operations (Details) ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018CNY (¥)	Dec. 31, 2018USD ($)	Dec. 31, 2017CNY (¥)	Dec. 31, 2016CNY (¥)
Income Tax Disclosure [Abstract]
Loss before income tax expenses	¥ (928,660)		¥ (913,824)	¥ (253,567)
Income tax expenses computed at applicable tax rates of 25%	(232,165)		(228,456)	(63,392)
Non-deductible and super deduction expenses	(8,013)		(3,490)	2,477
Effect of tax holidays and preferential tax rates	64,029		130,296	24,808
Change in valuation allowance	176,149		101,650	36,107
Income tax expenses	¥ 0	$ 0	¥ 0	¥ 0

Income Taxes - Schedule of Re_2

Income Taxes - Schedule of Reconciliation of Effective Tax Rate and Statutory Income Tax Rate Applicable to PRC Operations (Parenthetical) (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Statutory income tax rate	25.00%	25.00%	25.00%

Income Taxes - Schedule of Comp

Income Taxes - Schedule of Components of Deferred Income Tax (Details) - CNY (¥) ¥ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Non-current deferred tax assets
Accrued expenses	¥ 13,270	¥ 5,108
Advertising expenses carry-forwards	87,600	87,600
Net operating loss carry-forwards	285,018	117,031
Total non-current deferred tax assets	385,888	209,739
Less: valuation allowance	(385,888)	(209,739)
Non-current deferred tax assets, net	0	0
Total non-current deferred tax liabilities	¥ 0	¥ 0

Net Loss Per Share - Schedule o

Net Loss Per Share - Schedule of Calculation of Net Loss Per Share (Details) ¥ / shares in Units, $ / shares in Units, ¥ in Thousands, $ in Thousands		12 Months Ended
		Dec. 31, 2018CNY (¥)¥ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017CNY (¥)¥ / sharesshares	Dec. 31, 2016CNY (¥)¥ / sharesshares
Net loss attributable to Sunlands Technology Group used in basic and diluted net loss per share:
Net loss attributable to ordinary shareholders		¥ (927,022)	$ (134,830)	¥ (918,578)	¥ (253,567)
Denominator:
Weighted average ordinary shares outstanding used in computing basic and diluted net loss per share	[1]	6,294,870	6,294,870	3,945,864	3,818,618
Net loss per share
Basic and diluted | (per share)		¥ (147.27)	$ (21.42)	¥ (232.80)	¥ (66.40)
[1]	Each 25 American depositary shares ("ADSs") represents one of the Company's Class A ordinary shares.

Net Loss Per Share - Additional

Net Loss Per Share - Additional Information (Details) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee Stock Option
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	51,831
Series A Preferred Shares
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share		954,274	520,161
Series B Preferred Shares
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share		826,389
Series B+ Preferred Shares
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share		141,264

Amounts Due From_To Related P_3

Amounts Due From/To Related Parties - Summary of Related Party Transactions (Details) ¥ in Thousands	Dec. 31, 2017CNY (¥)
Related Party Transactions [Abstract]
Disposal of a subsidiary to a related party	¥ 1,000

Amounts Due From_To Related P_4

Amounts Due From/To Related Parties - Additional Information - (Details) - CNY (¥) ¥ in Thousands	12 Months Ended
	Dec. 31, 2017	Oct. 31, 2017
Related Party Transaction [Line Items]
Disposal of a subsidiary to a related party	¥ 1,000
Shangde Jiaxun
Related Party Transaction [Line Items]
Disposal of a subsidiary to a related party	1,000	¥ 1,000
Gain on disposition of assets	¥ 178

Amounts Due From_To Related P_5

Amounts Due From/To Related Parties - Summary of Aggregate Amounts Due from Related Parties (Details) ¥ in Thousands	Dec. 31, 2017CNY (¥)
Related Party Transaction [Line Items]
Amounts due from related parties	¥ 250,096
Shangde Jiaxun
Related Party Transaction [Line Items]
Amounts due from related parties	8,018	[1]
Elite Concept Holdings Limited
Related Party Transaction [Line Items]
Amounts due from related parties	162,000	[2]
Shanghai Chuang Ji
Related Party Transaction [Line Items]
Amounts due from related parties	80,000	[2]
Shenzhen Xingwang
Related Party Transaction [Line Items]
Amounts due from related parties	¥ 78	[2]
[1]	The balances as of December 31, 2017 included the consideration receivable of RMB1,000 from disposal of a subsidiary. The remaining balance of RMB7,018 were interest-free, unsecured and repayable on demand. The balance as of December 31, 2017 was fully repaid in February 2018.
[2]	The balances as of December 31, 2017 represented the original investments of RMB242,078 in Series A Equity Interest withdrew from Beijing Sunlands by certain Series A Preferred Shareholders which were reinvested in full to the Company in January 2018 (Note 13).

Amounts Due From_To Related P_6

Amounts Due From/To Related Parties - Summary of Aggregate Amounts Due from Related Parties (Parenthetical) (Details) - CNY (¥)	Dec. 31, 2018	Dec. 31, 2017	Oct. 31, 2017
Related Party Transaction [Line Items]
Disposal of a subsidiary to a related party		¥ 1,000,000
Amounts due to related parties	¥ 0	0
Series A Equity Interest
Related Party Transaction [Line Items]
Amount of original investments		242,078,000
Shangde Jiaxun
Related Party Transaction [Line Items]
Disposal of a subsidiary to a related party		1,000,000	¥ 1,000,000
Disposal of a subsidiary to a related party, remaining balance		¥ 7,018,000

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Future Minimum Payments Under Non-Cancelable Operating Leases to Offices and Public Displays With Initial Terms of One-Year or Longer (Details) ¥ in Thousands	Dec. 31, 2018CNY (¥)
Commitments And Contingencies Disclosure [Abstract]
2019	¥ 110,796
2020	97,949
2021	90,347
2022	83,251
2023 and thereafter	698,995
Operating leases, future minimum payments due, Total	¥ 1,081,338

Commitment and Contingencies -

Commitment and Contingencies - Additional Information (Details) - CNY (¥) ¥ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Commitments And Contingencies Disclosure [Line Items]
Total operating lease expense	¥ 107,331	¥ 65,214	¥ 53,714
Long-term Investments
Commitments And Contingencies Disclosure [Line Items]
Investment commitment amount	¥ 25,000

Segment Reporting - Additional

Segment Reporting - Additional Information (Details) - Segment	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting [Abstract]
Number of operating segments	1	1	1

Employee Defined Contribution_2

Employee Defined Contribution Plan - Additional Information (Details) - CNY (¥) ¥ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Compensation And Retirement Disclosure [Abstract]
Amounts expensed as incurred for employee defined contribution plan	¥ 228,376	¥ 164,775	¥ 64,189

Restricted Net Assets - Additio

Restricted Net Assets - Additional Information (Details) ¥ in Thousands	12 Months Ended
	Dec. 31, 2018CNY (¥)
Restricted Net Assets [Abstract]
Required minimum percentage of after-tax-profit allocated to general reserve	10.00%
Threshold percentage of general reserve of the registered capital	50.00%
Required minimum percentage of after-tax-profit allocated to statutory common reserve	10.00%
Threshold percentage of statutory common reserve of the registered capital, used as criteria of allocation requirement	50.00%
Amount of restricted paid-in-capital and statutory reserves	¥ 1,986

Financial Statement Schedule I

Financial Statement Schedule I - Condensed Financial Information of Parent Company Balance Sheets (Details) ¥ in Thousands, $ in Thousands	Dec. 31, 2018CNY (¥)	Dec. 31, 2018USD ($)	Dec. 31, 2017CNY (¥)	Dec. 31, 2016CNY (¥)	Dec. 31, 2015CNY (¥)
ASSETS
Cash and cash equivalents	¥ 1,248,810	$ 181,632	¥ 559,459
Short-term investments	1,028,564	149,598	353,070
Prepaid expenses and other current assets	124,908	18,169	48,993
Amounts due from related parties			250,096
Total current assets	2,582,939	375,674	1,266,691
TOTAL ASSETS	3,739,138	543,836	1,969,659
Current liabilities
Accrued expenses and other current liabilities	455,284	66,218	235,900
Total current liabilities	2,314,409	336,617	1,802,244
Non-current liabilities
Other non-current liabilities	17,147	2,494
Total non-current liabilities	1,763,712	256,522	784,474
TOTAL LIABILITIES	4,078,121	593,139	2,586,718
MEZZANINE EQUITY
TOTAL MEZZANINE EQUITY			1,024,709
SHAREHOLDERS’ DEFICIT
Ordinary shares			1
Additional paid-in capital	2,391,822	347,876	289,674
Accumulated other comprehensive (loss)/income	118,827	17,283	(8,759)
Accumulated deficit	(2,849,770)	(414,482)	(1,922,748)
TOTAL SHAREHOLDERS’ DEFICIT	(338,983)	(49,303)	(1,641,768)	¥ (888,955)	¥ (371,744)
TOTAL LIABILITIES, MEZZANINE EQUITY AND SHAREHOLDERS’ DEFICIT	3,739,138	543,836	1,969,659
Series A Convertible Redeemable Preferred Shares
MEZZANINE EQUITY
TOTAL MEZZANINE EQUITY			292,000
Series B Convertible Redeemable Preferred Shares
MEZZANINE EQUITY
TOTAL MEZZANINE EQUITY			601,605
Series B+ Convertible Redeemable Preferred Shares
MEZZANINE EQUITY
TOTAL MEZZANINE EQUITY			131,104
Class A Ordinary Shares
SHAREHOLDERS’ DEFICIT
Ordinary shares	1
Treasury stock	(34,828)
TOTAL SHAREHOLDERS’ DEFICIT	1
Class B Ordinary Shares
SHAREHOLDERS’ DEFICIT
Ordinary shares	0	0	0
Class C Ordinary Shares
SHAREHOLDERS’ DEFICIT
Ordinary shares	1
TOTAL SHAREHOLDERS’ DEFICIT	1
Parent Company
ASSETS
Cash and cash equivalents	1,086,521	158,028	155,652
Short-term investments	441,513	64,215	0
Prepaid expenses and other current assets	11,950	1,738	0
Amounts due from subsidiaries	695,194	101,112	509,657
Amounts due from related parties	0	0	242,078
Total current assets	2,235,178	325,093	907,387
TOTAL ASSETS	2,235,178	325,093	907,387
Current liabilities
Accrued expenses and other current liabilities	6,268	912	81
Total current liabilities	6,268	912	81
Non-current liabilities
Investment in subsidiaries	2,556,801	371,871	1,524,565
Other non-current liabilities	11,228	1,633	0
Total non-current liabilities	2,568,029	373,504	1,524,565
TOTAL LIABILITIES	2,574,297	374,416	1,524,646
MEZZANINE EQUITY
TOTAL MEZZANINE EQUITY	0	0	1,024,709
SHAREHOLDERS’ DEFICIT
Ordinary shares	0	0	1
Treasury stock	0	0	0
Additional paid-in capital	2,391,822	347,876	289,674
Accumulated other comprehensive (loss)/income	118,827	17,283	(8,759)
Accumulated deficit	(2,849,770)	(414,482)	(1,922,884)
TOTAL SHAREHOLDERS’ DEFICIT	(339,119)	(49,323)	(1,641,968)	¥ (888,955)	¥ (371,744)
TOTAL LIABILITIES, MEZZANINE EQUITY AND SHAREHOLDERS’ DEFICIT	2,235,178	325,093	907,387
Parent Company | Series A Convertible Redeemable Preferred Shares
MEZZANINE EQUITY
TOTAL MEZZANINE EQUITY	0	0	292,000
Parent Company | Series B Convertible Redeemable Preferred Shares
MEZZANINE EQUITY
TOTAL MEZZANINE EQUITY	0	0	601,605
Parent Company | Series B+ Convertible Redeemable Preferred Shares
MEZZANINE EQUITY
TOTAL MEZZANINE EQUITY	0	0	131,104
Parent Company | Class A Ordinary Shares
SHAREHOLDERS’ DEFICIT
Ordinary shares	1	0	0
TOTAL SHAREHOLDERS’ DEFICIT	1
Parent Company | Class B Ordinary Shares
SHAREHOLDERS’ DEFICIT
Ordinary shares	0	0	0
Parent Company | Class C Ordinary Shares
SHAREHOLDERS’ DEFICIT
Ordinary shares	1	$ 0	¥ 0
TOTAL SHAREHOLDERS’ DEFICIT	¥ 1

Financial Statement Schedule _2

Financial Statement Schedule I - Condensed Financial Information of Parent Company Balance Sheets (Parenthetical) (Details)	Dec. 31, 2018$ / sharesshares	Mar. 31, 2018shares	Dec. 31, 2017$ / sharesshares	Sep. 18, 2015$ / sharesshares	Sep. 18, 2015¥ / sharesshares
Condensed Financial Statements Captions [Line Items]
Ordinary shares, par value | (per share)	$ 0.00005		$ 0.00005	$ 0.00005	¥ 0.0003
Ordinary shares, shares authorized	1,000,000,000		1,000,000,000	1,000,000,000	1,000,000,000
Ordinary shares, shares issued			4,329,000	1	1
Ordinary shares, shares outstanding		4,329,000	4,329,000
Class A Ordinary Shares
Condensed Financial Statements Captions [Line Items]
Ordinary shares, par value | $ / shares	$ 0.00005		$ 0.00005
Ordinary shares, shares authorized	796,062,195		796,062,195
Ordinary shares, shares issued	1,818,383
Ordinary shares, shares outstanding	1,773,301	63,714
Class B Ordinary Shares
Condensed Financial Statements Captions [Line Items]
Ordinary shares, par value | $ / shares	$ 0.00005		$ 0.00005
Ordinary shares, shares authorized	826,389		826,389
Ordinary shares, shares issued	826,389
Ordinary shares, shares outstanding	826,389
Class C Ordinary Shares
Condensed Financial Statements Captions [Line Items]
Ordinary shares, par value | $ / shares	$ 0.00005		$ 0.00005
Ordinary shares, shares authorized	203,111,416		203,111,416
Ordinary shares, shares issued	4,265,286
Ordinary shares, shares outstanding	4,265,286	4,265,286
Parent Company
Condensed Financial Statements Captions [Line Items]
Ordinary shares, par value | $ / shares	$ 0.00005		$ 0.00005
Ordinary shares, shares authorized	1,000,000,000		1,000,000,000
Ordinary shares, shares issued	0		4,329,000
Ordinary shares, shares outstanding	0		4,329,000
Parent Company | Class A Ordinary Shares
Condensed Financial Statements Captions [Line Items]
Ordinary shares, par value | $ / shares	$ 0.00005		$ 0.00005
Ordinary shares, shares authorized	796,062,195		796,062,195
Ordinary shares, shares issued	1,818,383		0
Ordinary shares, shares outstanding	1,773,301		0
Parent Company | Class B Ordinary Shares
Condensed Financial Statements Captions [Line Items]
Ordinary shares, par value | $ / shares	$ 0.00005		$ 0.00005
Ordinary shares, shares authorized	826,389		826,389
Ordinary shares, shares issued	826,389		0
Ordinary shares, shares outstanding	826,389		0
Parent Company | Class C Ordinary Shares
Condensed Financial Statements Captions [Line Items]
Ordinary shares, par value | $ / shares	$ 0.00005		$ 0.00005
Ordinary shares, shares authorized	203,111,416		203,111,416
Ordinary shares, shares issued	4,265,286		0
Ordinary shares, shares outstanding	4,265,286		0

Financial Statement Schedule _3

Financial Statement Schedule I - Condensed Financial Information of Parent Company Statements of Operations (Details) ¥ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018CNY (¥)	Dec. 31, 2018USD ($)	Dec. 31, 2017CNY (¥)	Dec. 31, 2016CNY (¥)
Cost of revenues	¥ 330,376	$ 48,051	¥ 170,261	¥ 70,986
Gross profit	1,643,609	239,053	799,901	347,924
Operating expenses
Sales and marketing expenses	(2,152,830)	(313,116)	(1,351,811)	(503,643)
General and administrative expenses	(443,691)	(64,532)	(342,906)	(89,390)
Total operating expenses	(2,672,543)	(388,705)	(1,727,579)	(606,965)
Loss from operations	(1,028,934)	(149,652)	(927,678)	(259,041)
Loss before income tax expenses	(928,660)	(135,069)	(913,824)	(253,567)
Income tax expenses	0	0	0	0
Net loss	(926,950)	(134,820)	(918,714)	(253,567)
Parent Company
Cost of revenues	(475)	(69)	(19,244)
Gross profit	(475)	(69)	(19,244)
Operating expenses
Sales and marketing expenses	(820)	(119)	(75,237)
General and administrative expenses	(15,335)	(2,230)	(194,878)	(4)
Total operating expenses	(16,155)	(2,349)	(270,115)	(4)
Loss from operations	(16,630)	(2,418)	(289,359)	(4)
Interest income	33,525	4,876	1,592
Loss before income tax expenses	16,895	2,458	(287,767)	(4)
Income tax expenses	0	0	0	0
Loss from investment in subsidiaries	(943,781)	(137,268)	(630,947)	(253,563)
Net loss	¥ (926,886)	$ (134,810)	¥ (918,714)	¥ (253,567)

Financial Statement Schedule _4

Financial Statement Schedule I - Condensed Financial Information of Parent Company Statements of Changes in Shareholders' Deficit (Details) ¥ in Thousands, $ in Thousands		1 Months Ended	12 Months Ended
		Mar. 31, 2018shares	Dec. 31, 2018CNY (¥)shares	Dec. 31, 2018USD ($)shares	Dec. 31, 2017CNY (¥)shares	Dec. 31, 2016CNY (¥)shares
Balances			¥ (1,641,768)		¥ (888,955)	¥ (371,744)
Balances (in shares) | shares			4,329,000	4,329,000
Net loss for the year			¥ (926,950)	$ (134,820)	(918,714)	(253,567)
Recapitalization in connection with the Group’s 2016 reorganization						(293,644)
Capital contribution from equity shareholders						30,000
Capital contribution from a noncontrolling shareholder					200
Repurchase of equity from shareholders	[1]				(71,303)
Cash dividend to a Series A convertible redeemable preferred shareholder					(43,000)
Issuance of ordinary shares, net of issuance cost			1,109,517
Conversion of convertible redeemable preferred shares upon initial public offering			1,024,709
Stock Repurchased During Period, Value			34,828
Share-based compensation			2,751		288,763
Change in cumulative foreign currency translation adjustments			127,586	18,557	(8,759)
Balances			¥ (338,983)	$ (49,303)	¥ (1,641,768)	(888,955)
Balances (in shares) | shares		4,329,000			4,329,000
Class A Ordinary Shares
Ordinary shares newly issued | shares		659,131	659,131	659,131
Conversion of convertible redeemable preferred shares upon initial public offering			¥ 1
Conversion of convertible redeemable preferred shares upon initial public offering, shares | shares			1,159,252	1,159,252
Share repurchase, shares | shares			45,082	45,082
Balances			¥ 1
Balances (in shares) | shares		63,714	1,773,301	1,773,301
Class B Ordinary Shares
Conversion of convertible redeemable preferred shares upon initial public offering, shares | shares			826,389	826,389
Balances (in shares) | shares			826,389	826,389
Class C Ordinary Shares
Conversion of convertible redeemable preferred shares upon initial public offering			¥ 1
Conversion of convertible redeemable preferred shares upon initial public offering, shares | shares			4,265,286	4,265,286
Balances			¥ 1
Balances (in shares) | shares		4,265,286	4,265,286	4,265,286
Additional Ordinary Shares
Balances			¥ 1		¥ 1	¥ 1
Balances (in shares) | shares			4,329,000	4,329,000	3,818,618	3,818,618
Shares issuance in relation to share-based compensation (Note 16), shares | shares					510,382
Conversion of convertible redeemable preferred shares upon initial public offering			¥ (1)
Conversion of convertible redeemable preferred shares upon initial public offering, shares | shares			(4,329,000)	(4,329,000)
Balances					¥ 1	¥ 1
Balances (in shares) | shares					4,329,000	3,818,618
Additional Paid-in Capital
Balances			¥ 289,674		¥ 30,911	¥ 911
Capital contribution from equity shareholders						30,000
Repurchase of equity from shareholders	[1]				(30,000)
Issuance of ordinary shares, net of issuance cost			1,109,517
Conversion of convertible redeemable preferred shares upon initial public offering			1,024,708
Stock Repurchased During Period, Value			34,828
Share-based compensation			2,751		288,763
Balances			2,391,822	$ 347,876	289,674	30,911
Accumulated Other Comprehensive (Loss)/Income
Balances			(8,759)
Change in cumulative foreign currency translation adjustments			127,586		(8,759)
Balances			118,827	17,283	(8,759)
Accumulated Deficit
Balances			(1,922,748)		(919,867)	(372,656)
Net loss for the year			(927,022)		(918,578)	(253,567)
Recapitalization in connection with the Group’s 2016 reorganization						(293,644)
Repurchase of equity from shareholders	[1]				(41,303)
Cash dividend to a Series A convertible redeemable preferred shareholder					(43,000)
Balances			¥ (2,849,770)	$ (414,482)	(1,922,748)	(919,867)
Treasury Stock
Share repurchase, shares | shares			(45,082)	(45,082)
Balances (in shares) | shares			45,082	45,082
Parent Company
Balances			¥ (1,641,968)		(888,955)	(371,744)
Balances (in shares) | shares			4,329,000	4,329,000
Net loss for the year			¥ (926,886)	$ (134,810)	(918,714)	(253,567)
Recapitalization in connection with the Group’s 2016 reorganization						(293,644)
Capital contribution from equity shareholders						30,000
Repurchase of equity from shareholders					(71,303)
Cash dividend to a Series A convertible redeemable preferred shareholder					(43,000)
Issuance of ordinary shares, net of issuance cost			1,109,517
Conversion of convertible redeemable preferred shares upon initial public offering			1,024,709
Stock Repurchased During Period, Value			(34,828)
Share-based compensation			2,751		288,763
Change in cumulative foreign currency translation adjustments			127,586		(8,759)
Balances			¥ (339,119)	$ (49,323)	¥ (1,641,968)	(888,955)
Balances (in shares) | shares			0	0	4,329,000
Parent Company | Class A Ordinary Shares
Balances (in shares) | shares			0	0
Ordinary shares newly issued | shares			659,131	659,131
Conversion of convertible redeemable preferred shares upon initial public offering			¥ 1
Conversion of convertible redeemable preferred shares upon initial public offering, shares | shares			1,159,252	1,159,252
Share repurchase, shares | shares			(45,082)	(45,082)
Balances			¥ 1
Balances (in shares) | shares			1,773,301	1,773,301	0
Parent Company | Class B Ordinary Shares
Balances (in shares) | shares			0	0
Conversion of convertible redeemable preferred shares upon initial public offering, shares | shares			826,389	826,389
Balances (in shares) | shares			826,389	826,389	0
Parent Company | Class C Ordinary Shares
Balances (in shares) | shares			0	0
Conversion of convertible redeemable preferred shares upon initial public offering			¥ 1
Conversion of convertible redeemable preferred shares upon initial public offering, shares | shares			4,265,286	4,265,286
Balances			¥ 1
Balances (in shares) | shares			4,265,286	4,265,286	0
Parent Company | Additional Ordinary Shares
Balances			¥ 1		¥ 1	¥ 1
Balances (in shares) | shares			4,329,000	4,329,000	3,818,618	3,818,618
Shares issuance in relation to share-based compensation (Note 16), shares | shares					510,382
Conversion of convertible redeemable preferred shares upon initial public offering			¥ (1)
Conversion of convertible redeemable preferred shares upon initial public offering, shares | shares			(4,329,000)	(4,329,000)
Balances					¥ 1	¥ 1
Balances (in shares) | shares					4,329,000	3,818,618
Parent Company | Additional Paid-in Capital
Balances			¥ 289,674		¥ 30,911	¥ 911
Capital contribution from equity shareholders						30,000
Repurchase of equity from shareholders					(30,000)
Issuance of ordinary shares, net of issuance cost			1,109,517
Conversion of convertible redeemable preferred shares upon initial public offering			1,024,708
Stock Repurchased During Period, Value			(34,828)
Share-based compensation			2,751		288,763
Balances			2,391,822	$ 347,876	289,674	30,911
Parent Company | Accumulated Other Comprehensive (Loss)/Income
Balances			(8,759)
Change in cumulative foreign currency translation adjustments			127,586		(8,759)
Balances			118,827	17,283	(8,759)
Parent Company | Accumulated Deficit
Balances			(1,922,884)		(919,867)	(372,656)
Net loss for the year			(926,886)		(918,714)	(253,567)
Recapitalization in connection with the Group’s 2016 reorganization						(293,644)
Repurchase of equity from shareholders					(41,303)
Cash dividend to a Series A convertible redeemable preferred shareholder					(43,000)
Balances			¥ (2,849,770)	$ (414,482)	¥ (1,922,884)	¥ (919,867)
Parent Company | Treasury Stock
Share repurchase, shares | shares			45,082	45,082
Balances (in shares) | shares			45,082	45,082
[1]	In July 2017, Beijing Shangde Online Education Technology Co., Ltd. (“Beijing Sunlands”) repurchased equity interests held by certain shareholders at a total cash consideration of RMB71,303. Such equity interests of Beijing Sunlands were originally acquired at a cost of RMB30,000.

Financial Statement Schedule _5

Financial Statement Schedule I - Condensed Financial Information of Parent Company Statements of Changes in Shareholders' Deficit (Parenthetical) (Details) - CNY (¥) ¥ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Statement Of Stockholders Equity [Abstract]
Stock issuance costs	¥ 80,128	¥ 80,128	¥ 80,128

Financial Statement Schedule _6

Financial Statement Schedule I - Condensed Financial Information of Parent Company Statements of Cash Flows (Details) ¥ in Thousands, $ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2018CNY (¥)	Dec. 31, 2018CNY (¥)	Dec. 31, 2018USD ($)	Dec. 31, 2017CNY (¥)	Dec. 31, 2016CNY (¥)
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss		¥ (926,950)	$ (134,820)	¥ (918,714)	¥ (253,567)
Adjustments to reconcile net loss to net cash generated from operating activities:
Share-based compensation		3,851	560	288,763
Loss from investment in subsidiaries		(1,710)	(249)	4,890
Prepaid expenses and other current assets		(92,291)	(13,420)	(30,222)	3,139
Other non-current assets		(4,286)	(623)	(7,480)	(914)
Accrued expenses and other current liabilities		214,697	31,226	164,245	35,710
Net cash generated from operating activities		180,543	26,260	819,538	89,272
CASH FLOWS FROM INVESTING ACTIVITIES
Purchase of short-term investments		(4,352,103)	(632,987)	(2,139,097)	(858,500)
Disposal of short-term investments		3,708,810	539,424	1,931,027	757,500
Net cash used in investing activities		(1,186,721)	(172,602)	(615,895)	(117,695)
CASH FLOWS FROM FINANCING ACTIVITIES
Amounts due from related parties		253,672	36,895	7,944	(276)
Payment for share repurchase					(24,000)
Proceeds from initial public offering, net of issuance cost of 80,128	¥ 1,109,517	1,109,517	161,373
Capital contribution from Series B and B+ convertible redeemable preferred shareholders				732,709
Net cash generated from financing activities		1,587,343	230,869	341,472	47,080
Effect of exchange rate changes		108,186	15,735	(8,759)
Net increase in cash and cash equivalents		689,351	100,262	536,356	18,657
Cash and cash equivalents at beginning of the year		559,459	81,370	23,103	4,446
Cash and cash equivalents at end of the year		1,248,810	181,632	559,459	23,103
Parent Company
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss		(926,886)	(134,810)	(918,714)	(253,567)
Adjustments to reconcile net loss to net cash generated from operating activities:
Share-based compensation		3,851	560	288,763
Loss from investment in subsidiaries		1,032,235	150,132	813,313	253,563
Amounts due to subsidiaries		(185,537)	(26,985)	(751,735)
Prepaid expenses and other current assets		(19,276)	(2,804)
Other non-current assets		11,228	1,633
Accrued expenses and other current liabilities		4,231	615	75	¥ 4
Net cash generated from operating activities		(80,154)	(11,659)	(568,298)
CASH FLOWS FROM INVESTING ACTIVITIES
Purchase of short-term investments		(814,539)	(118,470)
Disposal of short-term investments		396,852	57,720
Net cash used in investing activities		(417,687)	(60,750)
CASH FLOWS FROM FINANCING ACTIVITIES
Amounts due from related parties		245,654	35,729
Payment for share repurchase		(33,971)	(4,941)
Proceeds from initial public offering, net of issuance cost of 80,128		1,109,517	161,373
Capital contribution from Series B and B+ convertible redeemable preferred shareholders				732,709
Net cash generated from financing activities		1,321,200	192,161	732,709
Effect of exchange rate changes		107,510	15,637	(8,759)
Net increase in cash and cash equivalents		930,869	135,389	155,652
Cash and cash equivalents at beginning of the year		155,652	22,639
Cash and cash equivalents at end of the year		¥ 1,086,521	$ 158,028	¥ 155,652

Financial Statement Schedule _7

Financial Statement Schedule I - Condensed Financial Information of Parent Company Statements of Cash Flows (Parenthetical) (Details) - CNY (¥) ¥ in Thousands	1 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017
Statement Of Cash Flows [Abstract]
Net of issuance cost	¥ 80,128	¥ 80,128	¥ 80,128