Taking the relevant data of listed companies from 2008 to 2020 as a sample, the article examines the impact of classification reform on the business performance of commercial state-owned enterprises by means of a double-difference model. The study found that the classification reform significantly improved the business performance of commercial state-owned enterprises. It contributes to the business performance of commercial state-owned enterprises by weakening policy burdens, reducing principal-agent costs and enhancing the degree of mixed ownership. In terms of the external environment, the classification reform has a stronger effect on the business performance of commercial state-owned enterprises in coastal areas than that in inland areas. And in terms of enterprise attributes, the classification reform has a stronger effect on the business performance of commercially competitive state-owned enterprises and central state-owned enterprises than that of function-specific state-owned enterprises and local state-owned enterprises.