Food concerns national livelihood and food security is vital for national security. In the context of "dual circulation" (i.e., domestic and international economic circulation) in China, clarifying the basic situation and challenges of food security and exploring effective strategies for food development are crucial for ensuring stable national development. Using national macro statistics, we first analyzed the basic situation of food security in China and the challenges it faces in the context of "dual circulation". Subsequently, we made a macro study on national food security and proposed the goals, strategic paths, major projects, and feasible countermeasures for ensuring national food security. Our study indicates that there exists a large gap between food supply and demand, a high degree of external dependence, and a large amount of imports of feed protein in China, as well as challenges including the difficulty in substituting feed protein domestically, rigidness of environmental restrictions on soil and water resources, low incentives for farmers to grow grains, and insufficient risk-resistant capabilities of the food security system. Moreover, we proposed a series of major projects, such as demonstration for upgrading grain production capacity, new protein resource substitution, green and lowcarbon planting and breeding circulation, development and utilization of international grain resources, and research and development demonstration of future foods. Several development strategies were further suggested, including the establishment of a food security guarantee system, moderate expansion of cultivated land areas, sustained increase in oil-bearing plant production, steady resumption of a multiple cropping system in South China, and sustained advancement of a rotational cropping system in North China.