EXHIBIT 31.1
                                  CERTIFICATION

I, Jack Lin, certify that:

1.  I have reviewed  this  quarterly  report on Form 10-Q of National  Technical
    Systems, Inc.;

2.  Based on my knowledge,  this report does not contain any untrue statement of
    a  material  fact or omit to state a  material  fact  necessary  to make the
    statements made, in light of the  circumstances  under which such statements
    were made, not misleading with respect to the period covered by this report;

3.  Based  on my  knowledge,  the  financial  statements,  and  other  financial
    information included in this report, fairly present in all material respects
    the  financial  condition,  results  of  operations  and  cash  flows of the
    registrant as of, and for, the periods presented in this report;

4.  The  registrant's  other  certifying  officers  and  I are  responsible  for
    establishing and maintaining  disclosure controls and procedures (as defined
    in Exchange Act Rules 13a-15(e) and 15d-15(e)) for the registrant and have:

    a)   designed  such  disclosure  controls  and  procedures,  or caused  such
         disclosure   controls  and   procedures   to  be  designed   under  our
         supervision,  to  ensure  that  material  information  relating  to the
         registrant,  including its consolidated subsidiaries,  is made known to
         us by others within those entities,  particularly  during the period in
         which this report is being prepared;

    b)   evaluated the effectiveness of the registrant's disclosure controls and
         procedures  and  presented  in this  report our  conclusions  about the
         effectiveness of the disclosure controls and procedures,  as of the end
         of the period covered by this report based on such evaluation; and

    c)   disclosed  in this  report  any  change  in the  registrant's  internal
         control over financial  reporting that occurred during the registrant's
         most recent fiscal quarter (the  registrant's  fourth fiscal quarter in
         the case of an  annual  report)  that has  materially  affected,  or is
         reasonably  likely to  materially  affect,  the  registrant's  internal
         control over financial reporting; and

5.  The registrant's other certifying officer and I have disclosed, based on our
    most recent evaluation of internal control over financial reporting,  to the
    registrant's  auditors and the audit committee of the registrant's  board of
    directors (or persons performing the equivalent functions):

    a)   all significant  deficiencies and material  weaknesses in the design or
         operation  of  internal  control  over  financial  reporting  which are
         reasonably  likely to  adversely  affect  the  registrant's  ability to
         record, process, summarize and report financial information; and

    b)   any fraud,  whether or not material,  that involves management or other
         employees  who have a  significant  role in the  registrant's  internal
         control over financial reporting.

                                             /s/ Jack Lin
                                             ------------
                                             Jack Lin,
                                             Principal Executive Officer and
                                             Chairman of the Board

                                                                 June 10, 2004