SWA T model is one of the most active non point source pollution models. Combined with GIS，it can simulate non-point source pollution under the different conditions of land use in complex large river basin. This study is based on the basic database of non-point source pollution and the integrity of the measured data and uses the GIS integration with the SWAT 2000 model.Model parameters are estimated using the measured data of water,sediment,and nutrient load from 1991 to 1996 and are verified using measured data from 1997 to 1998.Applicability and reliability of SWAT model in non point source pollution simulation in Heihe River basin are determined，which provides a reliable model foundation for non-point source pollution simulation in Heihe River basin of Shaanxi Province.