Based on the data of RSr, ainfall, DEM and soil, a study of soil erosion of the Catchment of Lake Hongfenghu located in karst ecological fragile area in Guizhou Province during the past 40 years (1960~2004) is taken by using GIS and RUSLE Model. The main contents of the research include: computing the annual amount of soil erosion, assessing the soil erosion intensity in the catchment of Lake Hongfeng during the periods of 1960~1986, 1987~1997 and 1998~2004, and discussing the relation between soil erosion and spatio-temporal changes of land use in the past 40 years. In the three periods, the special change of soil erosion intensity in the west has the character of getting more intense and then getting slight, but the relevant change is slight in the east of the drainage basin.