Using the sample of 6,890 bonds from 2010—2020, examine the impact mechanism of mixed ownership reform of urban investment company on their debt risk, and get the following conclusions: firstly, the excessive debt problem of urban investment enterprises becomes more serious after the mixed ownership reform. Secondly, in the long run, mixed ownership reform has improved the awareness of financial crisis of urban investment companies, and the profitability of enterprises has increased, thus reducing the motivation of excessive debt of enterprises. Thirdly, from the short-term perspective, administrative intervention is conducive to the mixed-ownership reform''s role in reducing the debt risk of urban investment enterprises, but from the long-term perspective, administrative intervention inhibits the mixed-ownership reform''s role in mitigating the debt risk of urban investment enterprises.Mixed ownership reform can reduce the debt risk of urban investment enterprises in the long run, but the premise is to give full play to the role of the market and reduce the government''s intervention in the transformation of urban investment enterprises. The research in this paper can provide enlightenment for the effective coordination of fiscal and financial policies at the micro level.