Duolun county, in central Inner Mongolia Autonomous Region, was selected as a typical region of ecotone between agriculture and animal husbandry in North China, and its' climate data, land desertification and land use data were comprehensively analyzed to find the in-depth formation mechanism of land desertification. Through analyzing the weather data of recent 30 years by linear trend method, results showed that the regional climate change made for the restoration of land desertification, and climate change was not the main reason for land desertification expansion and aggravation. Analyzing land desertification and land use observation data by means of spatial overlay and terrain statistics methods, the result showed that there was not obvious land use pattern change such as overcutting or overcultivating in the research region, and the land area without change of land use pattern accounted for 95.98% of the total land area. The aggravation of land desertification degree mainly occured in grassland and cultivatable land. The aggravation of desertification degree of these types land accounted for 55.16%, 25.92% and 10.31% of the whole, separately, and their sum accounted for 91.39% of total aggravation area of land desertification. Field survey and analyzing remote sensing, statistics etc. showed that cultivation in fall and use of agricultural machine gave rise to wind erosion of soil, and cultivation in successive years, plantation of economic crop such as sugar beet aggravated land degradation, then the heavy amount of yearly carrying livestock and traffic in grassland led to grassland degradation. Finally, according to these analysis results, land use adjustment plan was put forward.