Abstract: Taking A-share listed companies in Shanghai and Shenzhen from 2013 to 2020 as the research object, the multi-period difference-in-differences (DID) method and text analysis method were used to study the impact of implementation of key audit matters standards (referred to as guidelines, the same below) and text readability on institutional investors’ investigation behavior. The transmission mechanism of the impact of the implementation of the standards on the environment of corporate information disclosure was tested. Finally, the influence of key audit matters on institutional investor investigation was examined in the case of differences in the network media attention of different enterprises, the degree of accrued earnings management, the direction of real earnings management and the degree of local marketization. The results show that the implementation of the standards can reduce the number of institutional investors received by listed companies and the total number of institutional investor surveys in the fiscal year, and the readability of key audit items is negatively correlated with the investigation behavior of institutional investors. The implementation of the standards can improve the information disclosure environment of enterprises, and the impact of the implementation of the standard on institutional investors’ investigation behavior is more significant in enterprises with high network media attention, high degree of accrued earnings management, positive manipulation of real earnings management, and high degree of local marketization.