This study is based on the year-by-year investigation of nature, society, and economy in Zhangye City from 1998 to 2007. Driving forces of the changes of cultivated land and construction land were analyzed synthetically and quantitatively using mathematical statistics methods in order to discover the similarities and differences of driving forces. Results indicated that driving factors display a certain difference. At the same time, the direction and size of principal component factors are different. The level of economic development and economic structure factors make a negative driving to cultivated landuse change, but a positive driving to construction landuse change. The research result contributes to the quantitative and comparative under standing of driving forces on cultivated land and construction land and points out a way to the research on landuse change mechanisms.