Food security is the foundation of a country's social stability and economic development. This paper compares the global food security with China's food situation, summarizes the main problems of China's food security, and explores the factors that affect China's food security, including the shortage of agricultural land resources, the inability to meet the needs of food production, the rapid growth of food demand, the aggravation of the imbalance of food supply and the threat from the international market. Based on this, the paper puts forward suggestions of relevant policy to ensure national food security, in order to provide a scientific basis for the policy formulation of relevant government departments.