Taking the A-share listed companies in Shanghai and Shenzhen stock exchanges from 2013 to 2017 as a research sample, this paper empirically analyzes the different impacts of smog pollution on audit fees and audit quality of accounting firms. The empirical results show that smog pollution could lead to an increase in audit fees and a decline in audit quality. The results are still robust after replacing the smog pollution index, changing the measurement of smog pollution, replacing the smog pollution data, replacing audit quality index, replacing control variables, using extreme weather ratios, considering the expected effect of smog pollution and PSM. Further analysis indicates that smog pollution will increase audit fees by increasing the business risk of the enterprise and the risk of exposure of corporate issues.Smog pollution will reduce audit quality by shortening the auditor's audit time. Audit fees premium strengthens the negative impact of smog pollution on audit quality. The positive impact of smog pollution on audit fees and the negative impact on audit quality are only evident in the sample of non-heavy polluting enterprises and in the samples of non-heavy polluted areas. The conclusions of the paper are helpful to clarify the mechanism of the effects of smog pollution on auditing behavior,and provide a theoretical basis for the regulators to strengthen the supervision of the audit market in the smog environment.