Abstract: In this study, Soil and Water Assessment Tool (SWAT) was used to simulate the river discharge and Non-Point Source (NPS) pollution processes in the Shahe Reservoir catchment in Beijing. The model was run with data of ten years period (1999-2008). The simulation results of monthly discharge, total nitrogen (TN) and total phosphorus (TP) showed that the SWAT model performed satisfactorily in the study area (R2=0.77~0.85, Ens=0.60~0.64 for monthly discharge; R2=0.65~0.78, Ens=0.53~0.72 for TN and TP). The NPS pollution contribution increased with the precipitation, which accounted for 30%~50% of total pollution in different hydrologic years. Nanshahe sub-watershed was the critical area in the pollution. The sediment and TP accounted for 70% of the total volume in the flood period from June to September. In addition, seven scenarios ware set up to analyze the degree of NPS pollution within different hydrological conditions, landuses and management measures by using SWAT model. Results show that, if all point sources reach, the standard level, and all farmland is change into forest, discharge and pollutant loads will decrease by 45%~50%. Pollutant loads will decrease by nearly 20% with the decrease of fertilizer uses. Nitrogen load per unit area in ranks is: orchard> farmland> pasture> forest> urban land. This study provides important scientific basis for the planning and management of the water resources in the Shahe Reservoir catchment.