This paper analyzes and compares the key factors influencing food security in two populous countries (China and India), and categorizes them into three types: agricultural production, economic development and income level, and income distribution. Using the prevalence of undernourishment as an indicator of food security, the paper empirically tests the degree of impact of various factors on food security in both countries using Tobit regression and Newey regression methods. The study finds that improving the level of economic development can significantly enhance food security in both countries; reducing the Gini coefficient has a significant impact on India, but not on China; increasing the agricultural production per capita has a much greater effect on China than on India. Therefore, both countries should take measures that are both similar and different according to their national conditions to improve their food security level.