Based on the empirical data of A share main board listed companies in Shanghai and Shenzhen from 2011 to 2019, this paper investigates the impact of employee satisfaction on internal control quality. It is found that higher employee satisfaction can significantly improve the quality of the company’s internal control. It is further found that the enhancing effect of employee satisfaction on the quality of internal control is mainly realized through the alleviation of principal agent conflict, and that this effect exhibits significant heterogeneity among firms with different rule of law environments, industry competition, and degrees of production factor dependence. The analysis of economic consequences shows that employee satisfaction can reasonably ensure the realization of business objectives, reporting reliability objectives, and legal compliance objectives by improving the quality of internal control. The findings of the study not only provide empirical evidence for companies to continuously emphasize and increase investment in human capital, but also provide new ideas for companies to improve the quality of internal control.