The establishment and operation of the central and local audit committees in 2018 may have an important impact on budget implementation. We measure the deviation of budget with final accounts and the budget expenditure in the year from 2016 to 2020, and investigate the relationship between the establishment and operation of the audit committee of the Party committee and budget deviation. The study found that after the establishment and operation of the audit committee, the deviation of provincial expenditure budget decreased. When the financial transparency of the province is higher, the deviation will be reduced more. In the mechanism test, we found that the establishment and operation of the audit committee can improve the efficiency of expenditure budget management by strengthening the participation of local government leaders in economic supervision and improving the authority and independence of national audit, so as to reduce the deviation of expenditure budget. Further research also found that after the establishment of the audit committee, the more expenditure deviation, and the more problems will be audited and discovered. The conclusion of research provides empirical evidence for governance in the budgetary management of the committee, which is contributing to the profound understanding of the further reform of the audit management and the production of inspiration for promoting the country’s governance modernization.