Using the unified management reform of human and financial resources of sub provincial local audit institutions implemented in 2015 as a quasi natural experiment, the impact of the unified management reform of human and financial resources on audit quality is measured based on Chinese provincial panel data from 2007 to 2018, using synthetic control method to construct real reform pilot areas and synthetic reform areas. The study shows that (1) the reform can significantly improve audit quality in Guizhou province compared to unreformed provinces. Audit quality in Guizhou province improved by an average increase of 35,000 yuan per year from 2016 to 2018. The conclusion still holds after placebo test, ranking test, and mean square prediction error ratio test. (2) There is heterogeneity in the reform effect, with significant improvement in Guizhou, Shandong, Jiangsu, Zhejiang, and Guangdong provinces, some time lag in Chongqing municipality, and insignificant improvement in Yunnan province. (3) Compared with other pilot provinces, Guizhou province has the most thorough reform, and its reform experience has certain inspiration and guidance for further deepening the reform of audit management system and building a centralized, unified, comprehensive coverage, authoritative and efficient audit supervision system.