Food security is the greatest thing of the country. Food trade is one of the important measures to ensure food security. Based on the production and trade data of maize, rice, soybeans and wheat, combining the measurement of data indicators such as food production, food self-sufficiency rate, food import and export quantity and value, concentration rate of import, and Shannon entropy index, the article comprehensively and systematically sorts out the evolution of China's food security and trade pattern from 2000 to 2022. The results show that: ① The productions of maize, rice, soybeans and wheat are relatively stable and have increased to varying degrees in China. The self-sufficiency rates of maize, rice and wheat have always remained above 90%, which is at a safe level. However, the self-sufficiency rate of soybeans has declined rapidly, and the supply and demand risks are relatively large. ② The import of maize, rice, soybeans and wheat increased with varying degrees, while the corresponding exports have continued to decline. The concentration rate CR5 of maize, rice, soybeans and wheat imports are all higher, while the concentration rate CR3 and concentration rate CR1 fluctuate greatly. The main food importing countries of China are highly concentrated in a few countries, including the United States, Ukraine, Vietnam, Thailand, Brazil, Australia and Canada. China's dependence on the imports of maize and soybeans is higher than the imports of rice and wheat. ③ The security of China's import trade structure of main food is lower than that of its export trade structure. The import trade structures of maize and rice are primarily characterized as extremely insecure, while soybeans are moderately insecure, and wheat is mainly moderately insecure. The export trade structure of maize is mainly extremely insecure and moderately insecure, rice moderately secure and secure, soybeans slightly insecure and slightly secure, and wheat exhibits the greatest volatility in export trade structure security, with most years showing extremely insecure or slightly secure. ④ The food imports of China are restricted by key channels such as the Panama Canal, the Suez Canal and the Strait of Malacca, and are also facing threats such as monopoly control by world grain traders.