The security of food crop seed supply is an important basis for ensuring national food security. This report calculates the seed self-sufficiency rates of three major food crops under different constraints based on historical dimensional data and an analysis of the basic characteristics of food crop seed supply and demand，import and export，national reserves and enterprise stocks，as well as market prices. The results show that the self-sufficiency rates of hybrid rice，conventional rice，maize and wheat in China are all at high levels，with the lowest self-sufficiency rates of the four crops since 2013 being 119.9 percent，105.3 percent，110.6 percent and 132.5 percent，respectively. However，China’s seed supply still suffers from a wide range of seed varieties and serious homogenization of the same strains in the mid-range，resulting in a shortage of high-quality varieties in supply. Seed production areas are relatively concentrated and highly susceptible to extreme climate impacts. The separation between seed production areas and seed use areas is remote and the circulation pressure is high. The costs of seed production continue to rise，and the income of seed production enterprises and farmers decreases. It is difficult to predict market conditions in seed production plans，resulting in inventory surplus or out of stock. In order to improve the seed supply capacity，China should take market-oriented measures to increase the supply of high-quality seeds，enhance the emergency security capacity for seed supply，improve the modern technology level of seed production，reduce seed production costs，and encourage enterprises to expand foreign seed production markets.