With the current situation of food security still grim, food security is particularly important in pushing forward the overall rural revitalization and making China strong in modern agriculture. This paper took Nantong City, Jiangsu Province, a transition from grain production area to grain selling area, as an example, and analyzed the current situation of its cultivated land utilization, the grain type and distribution, grain production status, as well as the basic situation of grain enterprises, warehousing and circulation. It summarized the main practices and existing problems of ensuring food security in Nantong while the city develops fast in economy. Finally, the paper put forward policy recommendations to strengthen food security in four aspects including seeking distinctive developments, ensuring the total output of the cultivated land, increasing the production quality and efficiency, and integrating the agricultural industry chain.