Based on the data of listed companies in China's A-share manufacturing industry, multi-time point DID method (PSM-DID) based on propensity score matching was adopted to investigate the impact and mechanism of the robot application on the pay gap within company. The results show that the application of robots can significantly reduce the pay gap within company. The results remain robust after a series of robustness tests such as changing explanatory variables. The robot application can reduce the pay gap within company by promoting innovation and curbing earning management. Heterogeneity test results show that the impact of robot application on the intra-company pay gap is more significant in large and capital-intensive enterprises. Further research finds that the application of robots can significantly reduce the pay gap within company by reducing the excess pay of executives and then narrowing the excess pay gap. It provides a new perspective for exploring the governance mechanism of internal pay gap within company, and provides an important reference for China to realize income equity while promoting the transformation and upgrading of manufacturing industry.