Based on the analysis to the natural and artificial factors affecting the soil erosion of the mountainous region in western Guizhou province,it is thought that the region has been one of the areaswith the most serous soil and water loss in Guizhou province,which would harm the comprehensive exploitation serously to the watersheds of Wujiang river,meanwhile,threatening the developement of the national economy in the region and the safety of lives and properties.Having expounded the cause and harmness of several major types of erosion in the place,it points out that to strengthen the harmness of soil erosion of the region is the task of great urgency.