Revitalizing the real economy and preventing the “shift from real to virtual” is a strategic task of the supply-side structural reform. As an important channel for enterprises to obtain funds, how to promote banking and financial institutions to better serve the real economy has not been fully studied. Taking the Measures for the Administration of Joint Credit released by CBRC in 2018 as a quasi-experiment, this paper investigates the impact of the joint credit system on corporate financialization. The study shows that this policy significantly restrains corporate financialization, and the disincentive effect is more significantly in enterprises with lower information transparency or low shareholding of institutional investors. Mechanism testing shows that this policy restrains corporate financialization through inhibiting enterprise over-financing, and restraining shareholders’ tunneling behavior and managerial myopia. Further analysis shows that the joint credit system mainly restrains the allocation of short-term financial assets. Combined with the external environment, the study shows that the inhibitory effect is more significant in regions with a higher level of marketization. The economic consequences confirm that this policy promotes the increase of real capital investment and reduces the financial risk of enterprises by inhibiting corporate financialization. This paper not only provides microscopic empirical evidence for evaluating the effectiveness of the joint credit, but also provides reference for preventing the high leverage ratio of enterprises and promoting the financial supply-side reform.