This paper ishsed on the field observed data to study the effects of natural rainfall factors and slope steepnesson sheet erosion. The results show that the index of EI_(30) (prduct of kinetic energy and maximum thirty-minuteintensity of rainfall)which reflected the characteristics of rainfall and the potential energy of runoff which is a com-prehensive index of including rainfall factors and topographical factors are important factors on affecting the sheeterosion. The sheet erosion models with clear physical conceptions are presented by analysing, and these can be pro-vided analytical basis for establishing prediction models of soil erosion on sloping land.