EXHIBIT 12.1


                                 Certification

I, Chengyu Fu, Chairman and Chief Executive Officer of CNOOC Limited, certify
that:

1.    I have reviewed this annual report on Form 20-F of CNOOC Limited;

2.    Based on my knowledge, this annual 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 annual report;

3.    Based on my knowledge, the financial statements, and other financial
      information included in this annual 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 annual 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 annual report is being prepared;

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

      (c)   disclosed in this annual report any change in the registrant's
            internal control over financial reporting that occurred during the
            period covered by this 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 officers 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
      registrant's board of directors:

      (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.



Date:    June 26, 2006



                            By:  /s/ Chengyu Fu
                                -------------------------------------------
                                Name:    Chengyu Fu
                                Title:   Chairman and Chief Executive Officer