Abstract: This paper combines theoretical analysis with empirical test to explore the relationship between the diversity of board members' backgrounds and the innovation output of enterprises and the moderating effect of the effectiveness of internal control on their relationship. First, on the basis of the upper echelon theory, the resource dependence theory and the social cognition theory, two research hypotheses are put forward. Then the data of China's A-share listed companies from 2012 to 2018 are selected as the sample and two multiple linear regression models are established. The following conclusions are drawn with the method of Pearson, VIF, OLS and FE. First, there is a positive correlation between the background diversity of the board of directors and the output of corporate innovation, with a significant level of 1%. Second, on the significance level of 1%, the effectiveness of internal control has a positive regulating effect on the relationship between the diversity of the background of the board of directors and the innovation output of the enterprise. In other words, with the improvement of the effectiveness of internal control, the positive influence of the diversity of the background of the board of directors on the innovation output of the enterprise gradually increases. Third, in the state-held enterprises, the enterprises where the general manager and the chairman are separated and the enterprises in the areas with a high degree of marketization, the effectiveness of internal control has a stronger positive regulatory effect on the background diversity of the board of directors promoting corporate innovation.