5.12 汶川地震诱发大量的崩塌、滑坡、泥石流等新生水土流失问题，具有扰动强度大、影响范围广、破坏程度高等显著特点，水土流失状况加剧，已严重威胁震区社会经济与生态环境的可持续发展。通过采用统计分析方法，探讨地震前后不同生态系统类型的水土流失变化特征。结果显示，震后重灾区轻度水土流失面积比重呈降低趋势，中度和重度水土流失面积比重呈增加趋势。究其原因，震后重灾区农田、草地、森林生态系统的不同等级水土流失面积间存在一种动态转化关系，即轻度水土流失类型向中度和重度水土流失类型转化；相较于震区水土流失面积变化幅度而言，震后水土流失的程度和强度显著增加。

 Series of soil and water loss (SWL) problems, such as landslip, debris flow, and collapse, occurred due to “ 5.12 Wenchuan earthquake ” , which were characterized by high disturbance, extensive influence, and big destruction. The severe SWL had seriously threatened the sustainable development of society and environment in the earthquake area. On the basis of this, by adopting statistics method, this paper analyzes the soil loss change before and after Wenchuan earthquake. The results show that: the mild SWL area of farmland, grassland and forest ecosystem in the heavy earthquake area presents decrease tendency after earthquake, and moderate and severe SWL have increase tendency. After earthquake there exists dynamic transformation in different SWL grades, and mild SWL would change into moderate and severe SWL. Compared with the change of SWL area in earthquake area, after earthquake, the degree and intensity of SWL in the heavy earthquake area have a distinct increase.