This study empirically tests the impact of social insurance contribution adjustment on enterprises' resource allocation efficiency and its macroeconomic effect. It has been founded that increasing social insurance premium rate squeezes out enterprises' capital factor input， which makes it difficult for enterprises to maintain the growth model of over?reliance on demographic dividend， thus enterprises' overall resource allocation efficiency decreases significantly. Its rate increase has a crowding?out effect on investment in terms of raising labor cost， reducing internal cash flow and strengthening financing constraints. Meanwhile， by increasing the actual contribution amount， its rate increase makes thefinancially constrained firms reduce their labor input in the way of reducing the degree of insurance participation. Specifically， when the pension rate reduces to 16 percent， the aggregate productivity in all firms during the sample period increases by annual 4.24 percent on average， revealing that social insurance premium reductions help to improve firms' medium?and-long?term competitiveness from the cost side. This study is of great significance to deeply understand the micro enterprise transmission path of economic growth caused by premium reduction.