The difference between China's state-owned enterprises and private enterprises in credit access and production efficiency will distort the allocation of credit resources, thereby increasing macro leverage and increasing systemic risks. Based on the mortgage constraint mechanism, this paper constructs a dynamic stochastic general equilibrium model involving heterogeneous enterprises, theoretically analyzes the systemic risk formation mechanism caused by enterprise credit distortion, and discusses the coordination of the "dual pillar" regulation of monetary policy and macroprudential policy. It is found that in the heterogeneous enterprise environment, macroprudential policy can reduce macro leverage ratio, prevent systemic risks, and significantly improve social welfare losses by slowing down the procyclical behavior of the credit market, curbing excessive credit expansion, and significantly improving social welfare losses, creating more space for monetary policy formulation. The "dual-pillar" regulatory framework of monetary policy and macroprudential policy only slows down the amplification effect of the mortgage constraint mechanism on the economic cycle, and does not solve the problem of distortion of economic structure by heterogeneous enterprises. Therefore, deepening supply-side structural reform, improving the market competitiveness and self-financing capacity of state-owned enterprises, and giving full play to the role of the market in allocating resources are the keys to establishing a long-term mechanism for "deleveraging" and improving financial resilience to form a market environment that can endogenously digest risks.