The loess plateau in China is one of the most serious soil erosion areas. And the soil erosion volume of watershed is an
important index, which is useful to evaluate correctly the comprehensive management, and weigh the benefit of the comprehensive management. It is also the premise and foundation of arranging the measures of soil and water conservation and conducting watershed management and planning. Based on this, we deemed that simulating the soil erosion systems of
small watershed in loess area based on computer is essential. The computer based model of soil erosion of watershed in loess area was built. It is loosely coupled with
geographical information system. It makes use of DEMs function of providing the topographical feature, and then conducts the hydrological analysis of runoff in watershed. On the basis of this analysis, the USLE sediment model and the routing model were applied to the hydrological analysis of runoff. And then the distributed watershed soil erosion simulation model was built. Using this model, the soil erosion volume with different temporal and spatial characteristic can be computed. At last the research achievement applied to Huangjiaercha small watershed of Xiji county in Ningxia Hui Autonomous region. Additionally, the model system was verified to have a definite reliability. This will further heighten the level of small watershed comprehensive management of loess plateau in China.