Abstract: The traditional view is that high-quality external audit improves the quality of financial reports, and alleviates information asymmetry and principal-agent problems. However, there is no consensus on the research on the innovation effect of external audit quality in the existing literature. Based on the data of Chinese listed companies from 2008 to 2021, this paper empirically examines the innovation effect of audit quality and its mechanism from the perspectives of both scale and quality. The results show that higher audit quality not only promotes the increase of enterprise innovation output but also improves the quality of enterprise innovation. A series of endogeneity tests and robustness tests confirmed this conclusion. The mechanism test shows that higher audit quality can improve the quality of corporate information disclosure and promote positive news media coverage, thus promoting the improvement of the quantity and quality of patent output. Further analysis shows that for enterprises with few financing constraints and state-owned enterprises, audit quality has a significant promoting effect on the scale of innovation output. while for enterprises with high financing constraints and non-state-owned enterprises, the innovation scale effect of audit quality is not significant. In addition, the promotion effect of audit quality on innovation quality does not have heterogeneity characteristics based on financing constraints and the property rights of firms. This paper provides empirical evidence for an in-depth understanding of the relationship between audit quality and enterprise technological innovation and enriches the research on the innovation effect of audit quality.