Huanxian County of Gansu Province,located in the south part of farming-pastural ecotone,was selected as a study site,aiming to quantitative analyze the natural and anthropogenic factors of desertification inthis region.Principal component analysis was conducted on 16sets of data from 1949to 2009.The resultshowed that during the process of desertification,the contribution rate of combined natural and anthropogenic factors could be account for up to 49.64%,natural factors only contributed 21.79%,and anthropogenicfactors accounted for 10.89%,respectively.This demonstrated that natural and anthropogenic factors weredominating factors of desertification in Huanxian County.In addition,human activities played a decisive rolein desertification although climate condition also imposed substantial impacts.The effects of natural factors,including rising temperature,less rainfall,lower humidity,and higher evaporation potential restricted theplant growth and decreased vegetation coverage as well as the soil erosion resistance ability.In the otherhand,stronger winds and torrential rains could accelerate soil erosion.Anthropogenic factors including rapidly increased total population,oversized agricultural population,and subsequent excessive developing andgrazing are the direct factors of desertification in the study site.