Abstract: Soil desertification not only brings disaster and poverty to the people all of the world, but affects and limits economic development in western region of China. The paper first time explicated the interaction between natural factors and man-made factors during the process of soil desertification and the "Catalyst" action which caused by absurd economic activity during desertification's formation and evolution therrdiscussed genetic mech-anism of soil de}ertification in chaidamu basin area.