Soil erosion intensity relates closely with many vegetation and the soil factors, including the length of the slope and slope gradient，etc. . For the reason that traditional method in classifying the soil erosion of different patches in a watershed is inefficiency and inaccurate. We introduces how to use the functions of thenGIS spatial analysis and characteristic data of patches，to get the soil erosion classification map of watershed refered to the soil erosion intensity classification criterion. This method can quantifies the process of soil erosion intensity classifying, and being more scientific, modernized and rationalized.