Based on the data of A-share listed companies from 2011 to 2021, this paper measures audit risk with abnormal audit fees, and empirically investigates the influence and mechanism of digital finance on abnormal audit fees from the perspective of agency. Research has found that digital finance effectively alleviates the agency problem, significantly reduces the abnormal audit fees, and has a more prominent inhibitory effect on the positive abnormal audit fees. Reducing the agency cost of enterprises and restraining the real earnings management behavior of management have become the main channels. Further analysis shows that the deeper the use and digitization of digital finance, the lower the abnormal audit fees. In areas with good traditional financial development foundation and enterprises with high corporate governance efficiency, digital finance is more conducive to reducing abnormal audit fees. From the perspective of economic consequences, digital finance can further improve audit quality by reducing abnormal audit fees, and has played a positive role in reducing costs and improving audit quality.