Considering the factors of climate,hydrology,landforms,soil,vegetation and land u-tilization synthetically,handing the erosion of slope surface and ravine separately a new quanti-tative model is put out to calculate soil erosion in loess plateau by taking the minimum gully unit of DEM as the basic unit of soil erosion.Then taking the practice at Fugu county Shaanxiprovince for example the ecquisiton of model parameters is studied and tested with geographic information system(GIS)technology.