By using GIS and RS techniques and RUSLE, the rainfall erosivity (R), soil erodibility (K), vegetation and management factor (C), and slope length and steepness factor (LS) around Hangzhou Bay of Zhejiang Province, China were calculated to make a comprehensive sensitivity evaluation of soil erosion in the study area. In the meantime, the contribution of each natural factor, i. e., rainfall, soil texture, slope, and elevation, was analyzed, and a new approach, overlapping and ordering method, was developed to identify the key affecting factors in the given sensitive areas. In the study area, soil erosion was mainly at non-sensitive and low sensitive levels. The percentages of the areas with different soil erosion sensitivity varied with the strength of the affecting factors. Soil erosion sensitivity increased with increasing rainfall and slope, and the percentage of the area with high soil erosion sensitivity was the largest at elevation 200-500 meters. The overlapping and ordering method was a practicable approach in identifying the key affecting factors in given sensitive areas, being helpful to understand the mechanisms causing soil erosion.