With the increase of population, land carrying capacity and food safety have attracted great attention all over the world. From the point of man-grain relationship, on the basis of the theory of sustainable development and by using the land resources carrying capacity (LCCI) mode, the paper selected Gansu as the example that is the main dry land farming agricultural region in north western China. The results showed that: 1) General tendency of land resources carrying capacity improved in GanSu from 1985 to 2010, and grain possession increased gradually. However, the increasing population resulted in lacking of grain and overload. 2) The grain possession of Hexi Corridor was surplus and it was first in capacity in Gansu; Longdong Plateau kept balancing between population and grains in recent years, while the others such as Longzhong Plateau, Longnan Mountain and Gannan Plateau were overloaded. 3) Over the last 26 years (1985 - 2010), the number of overloading county in Hexi Corridor and Longdong Plateau decreased and the overloading counties mainly concentrated in agriculture developed regions, which indicated that the man-grain relationship was improved obviously during the past 26 years locally. 4) Based on the results, the man-grain contradiction in Gansu generally would keep stern for years although the carrying capacities of in some regions were improved.