The rocky desertification is a result of both nature processes and societal activities.Studying the driving mechanism of the rocky desertification is a prerequisite of restoring and rebuilding the karst fragile ecosystem.In order to quantify the effect of the climatic factor on the rocky desertification,all potential driving forces were selected including elements of physical geography,climate,population,community economy and the man) land relationships.These elements were correlated to a rocky desertification index,and the significant factors were then used in the patrtial least square(PLS) regression analysis.The significance of all kinds of driving factors for the rocky desertification were judged quantitatively by utilizing a variable importance projection(VIP)index.T he analysis shows that the physical geography element is the primary factor causing the rocky desertification,but the climatic element,especially precipitation amounts,is one of the direct driving forces,which increases as precipitation levels increase.