Considering the new situation of dietary structure transformation, frequent extreme weathers, and intensified international geopolitical conflicts, China needs to adopt an all-encompassing approach to food and exploit the food supply function of grassland agriculture to comprehensively improve its capability to ensure food security. Using qualitative and quantitative analysis, this study demonstrates the great value of developing grassland agriculture under the new situation, explores the trend of grassland agriculture development in typical countries, and summarizes its implications to China; furthermore, it evaluates the potential contribution of grassland agriculture to food security in China. The results show that rangeland has a great potential for providing high-quality livestock products and grassland agriculture can guarantee food security in rural areas. The agro-pastoral ecotones will be the major production bases for grassland-based livestock products and South China has dominant advantages in developing grassland agriculture. Therefore, we recommend to (1) strengthen rangeland restoration while rationally utilizing long-term grazing-prohibition rangelands, (2) regard forage as important as grain crop while strengthening grass breeding, (3) develop cultivated grasslands for gazing to relieve pressure on rangelands, (4) optimize the structure of livestock husbandry by promoting grain-saving grassland livestock husbandry, and (5) implement the strategy of "storing grain productivity in grassland" according to local conditions to enhance the food supply capacity of grassland.