According to erosivity and landform, soil erosions are divided into sheet erosion, gully erosion and gravity gully erosion. 1. Sheet erosion is the erosion caused by rain drop and overland flow. Because of the influence of landform and vegetation, sheet erosion mainly is the rill erosion. We use the equation of water balance and the relationship between vegetation and sediment yield are used to research the water balance on runoff plot, the influence of vegetation on sheet erosion, and sediment and runoff yield on plot; 2. Gully erosion is caused by concentrated flow coming from slope land and cliff; 3. Gravity gully is caused by mixed effect of gravity and runoff. In this paper we divided the gravity gully into three parts: Sheet flow effect part, gravity-runoff effect part, and transport-deposit part.