Soil erosion by water is affected by soil factor, rainfall erosivity, geographical factors, vegetation cover factor, and support practice factors. On the basis of quantitative estimation of soil erosion in the Upper Min River (UMR) watershed (located in the Upper Yangtze River basin, Sichuan, China) by applying the Revised Soil Loss Equation (RUSLE) model, Geographical Information System (GIS) software, and Remote Sensing (RS) technology, we explored the effects of topography and vegetation on soil loss for better erosion control measures, and analyzed ecological restoration approaches for the high soil erosion areas of this mountainous watershed. Totally 625 field plots were sampled for visually verifying soil erosion classification. Zonal statistics in ArcGIS software were used to assess the values of soil loss under different topographic and vegetation gradients. The results showed 58.1% of this watershed suffering moderate, high or extremely high erosion. The average soil erosion values substantially increased as the slope ranges rising. On the slopes of 7 categories (50 degrees), the percent of moderate, high and extreme risks accounted for 12.07%, 21.03%, 36.43%, 62.83%, 82.51%, 91.04%, and 94.02% respectively. The values of soil loss on sunny slopes were higher than those on shady slopes. The mean value was the greatest on the west-facing slope. On each similar slope, vegetation types showed different patterns to soil loss, and higher vegetation cover prevented more soil loss from erosion. In order to alleviate soil loss hazards, conservation measures to change micro-topography including terraces and contour tillage could be implemented in the watershed, and ecological restoration could be effective measure for controlling soil erosion in this degraded mountainous watershed.