At the beginning of 2020, the government launched the policy of enterprise social insurance premium reduction and exemption in response to the COVID-19 epidemic situation. Based on the new Keynes DGE and SGE theories, we construct a simulation analysis framework to test the macroeconomic effect of the policy. The results show that: first, the periodic social security fee relief policy is pointed and effective, and the policy has a strong short-term stimulus and long-term positive trend adjustment effect on the main variables of economic fundamentals.At the same time, the policy has a convergence effect with the financial expenditure expansion and interest rate decline relief policy. Secondly, it is difficult for China's economic fundamentals to support the long-term reduction and exemption of social security fees. Based on the analysis of the trend and stability, we should be cautious about the long-term expansion of the policy.