Using the data of Chinese listed companies from 2012 to 2014, this paper empirically tests the relationship between managerial overconfidence and corporate R & D investment in the context of financing constraints by the method of multiple regression analysis, and further tests the impact of ownership type on the relationship. We find that: 1) Compared with the companies with weak financing constraints, the positive relationship between managerial overconfidence and corporate R & D investment in the companies with strong financing constraints is stronger; 2) In the context of strong financing constraints, compared with the state-owned companies, the positive relationship between managerial overconfidence and corporate R & D investment in the non-state-owned companies is stronger.