Under the background of comprehensive and mandatory implementation of China’s internal control audit， with A-share listed companies in Shanghai and Shenzhen from 2013 to 2018 as the research sample， this paper makes an empirical analysis on the earnings quality and micro-mechanism of the listed companies implementing non-integrated audit，and uses the propensity score matching analysis method （PSM） to solve the problem of sample selection bias. The study finds that there is a significant difference in the improvement of earnings quality between integrated audit and non-integrated audit. Compared with the integrated audit，the implementation of non-integrated audit can significantly improve the earnings quality of listed company，while the implementation of non-integrated audit can significantly improve the effectiveness of internal control of the company. With the improvement of the effectiveness of internal control，the implementation of non-integrated auditing of enterprises has a more significant inhibitory effect on earnings management.