Abstract: Land-use /cover change(LUCC) study has been an important subject, since it was put forward. Its theoretical analysis has converted from pure natural analysis to the combination with natural and socio-economical analysis, from macroscopic global analysis to small regional analysis, from multiple type analysis for land use to single type.One of the dimensions of the studies is to study the human driving forces, which cause the changes. Cultivated land is one of the main type of land-use, and it is closely, correlative to population, spatial distribution of agricultural produce and natural factors such as soil, air temperature, topograghy and water condition. Cultivated land is an important basis source for a region's sustainable development and food security. With the development of economy, increase of population and expansion of city, cultivated land is faced with heavy pressure to raise and to hold more and more people on it. There are several cases studies of LUCC in China for cities such as Shanghai and Shenzhen, which are both the developed cities. What about mountainous area in middle-level developed province. The paper gives the quantitative changes and qualitative changes of cultivated land in eastern mountainous area of Jilin Province. Using correlation analysis and combining natural status, social status and economy status, we can get the causes of the dynamic change. With AHP, the conclusion is obtained that the decrease of the cultivated land in east mountainous area has close correlation with the increasing population, the level of agriculture skill, and economical policy.