ISSAIs is a framework of standards and guidelines for external auditing in the context of public sector issued by the INTOSAI Professional Standards Committee (PSC). Since 2011, the PSC has established the ISSAI Harmonization Project Group (HPG) to revise the ISSAI Harmonization Project of the PSC, continues to revise the ISSAI 100-999 Fundamental Auditing Principles，as a attenmpt to describe the general role and auditing function of a SAI and ensure the consistency between the different levels of ISSAIs.

Ever since its establishment, the CNAO has been an active member of HPG, and shared the duties to redraft ISSAI 100 (Fundamental Principles of Public Sector Auditing), ISSAI 200 (Fundamental Principles of Financial Audits), ISSAI 300 (Fundamental Principles of Performance Audits) and ISSAI 400 (Fundamental Principles of Compliance Audits). The CNAO representatives, mainly from the Resident Office in Chongqing and International Cooperation Department, have attended a series of teleconferences and London meeting held in January 19, 2012, concentrating on the revision of ISSAI 100.

The new version of ISSAI 100 has tried to provide a definition on the work of a SAI as well as the overall objective of auditing. By May 2012, the ISSAI 100 (exposure draft) as well as other ISSAI xxx, would be ready after the meeting of HPG in Copenhagen, Denmark and available for the discussion in the meeting of Steering Committee of PSC. The work of ISSAI 100 would be complete once it is approved by the XXI INCOSAI to be held in Beijing in 2013.