The steady increase in overall grain output is of great significance in accelerating to build up China’s strength in agriculture and in promoting the modernization of agriculture and rural development. This paper quantitatively analyzes grain policy documents from 1950 to 2022, constructs a partial equilibrium model of China’s grain market, captures the established impacts of policy implementation on grain market supply and demand, and simulates the impacts of possible future policy changes on grain market. Results show that: 1) The number of China""s grain policy documents and policy indexes have shown fluctuating growth and have demonstrated more obvious stage characteristics; 2) Grain security concerns, management and responsibilities have been progressively diversified, and policy formulation and implementation have been continuously implemented; 3) Grain policy implementation has a significant positive impact on grain unit yields and prices. An increase in the grain policy index contributes to an increase in the planted area and production per unit area, improving grain supply security and boosting domestic grain consumption for feed, forage and other purposes; a decrease in the grain policy index has the opposite effect. The role of grain policy on unit area yield is more obvious than the role of the planted area, the focus of grain production should be placed on improving yields. The implementation of the policy has a greater impact on the consumption of grain for feed than on consumption of grain for food, and the focus of future grain use should be on feed grains. To build up the “ballast stone” of grain security, this paper recommend enhancing the laws and regulations on grain policy, improving the continuity, stability and synergy of grain policy, and strengthening the construction of grain production capacity.