Based on the platform of Arcview 3.2,ARC/INFO 7.11 and Visual Foxpro 6.0,Soil erosion in the watershed of Jiuxihe in the up reach of Pearl River was evaluated by using universal soil loss equation(USLE).The factors related to soil erosion were inputted to Arcview in vector,which included topography,landuse,vegetation type,soil type,and converted to grid.Then cell based soil loss was calculated by using USLE based on map algebra.The result showed that:(1)In different landuse types,soil loss on wasteland was eight times that on the woodland.(2)Soil loss in economic forest was the biggest in different vegetation types.(3)Slope was the most important factor related to soil erosion,and soil loss on the land where slope was over 25,was fifty four times that on the flat.Afterward,the key factors and solution dealing with soil erosion harness were found out,which were slope and woodland.