Abstract: Cultivated land resources serve as an important basis for ensuring grain security. In recent years, the location of grain production has changed significantly because of the change of comparative advantage, which influences the functions of grain security of cultivated land. Taking Jiangsu Province, a main grain producing province, as an example, this paper studies the change of cultivated land dependence under the location changes. Through decoupling analysis and quantitative analysis, this study shows the differences of the dependence of cultivated land for grain production in Southern, Central and Northern areas of Jiangsu Province. And the dependence of cultivated land in Northern Jiangsu is much stronger than that in Central Jiangsu and Southern Jiangsu. As the Center of grain production gradually moves to Northern Jiangsu, the dependence of cultivated land for grain production at Jiangsu provincial level will gradually increase. The location evolution of grain production under the dominance by economic factors is not entirely reasonable. Therefore, to ensure the regional grain security, the government should properly promote the grain production in the north on the basis of a clear understanding of regional differences in endowments. At the same time, the government should improve the technology and the level of grain production, expand grain supply channels as well as alleviate the adverse effects from endowment differences in the process of evolution.