Using Chinese A-share listed companies from 2010 to 2022 as samples, this paper empirically shows that the performance expectation gap significantly reduces audit quality, and a series of robustness tests do not change the conclusion. Mechanism analysis shows that the performance expectation gap increases the risk of fraud, thus reducing audit quality. Heterogeneity analyses show that auditors with higher levels of independence and industry expertise are conducive to improving audit quality. Furthermore, the “Big Four” audits before COVID19 better play their external governance role, and the performance expectation gap has a significant positive impact on the persistence of low-quality audits. The findings expand the audit consequences of performance expectations gap and provide empirical evidence on how to promote the high-quality development of firms and the capital market.