SWAT model was used to calculate the agricultural non-point source pollution in Daninghe watershed.The runoff and the sediment data series from 2000 to 2004 were used to calibrate the parameters and validate the model.Results indicated that SWAT model was appropriate for Daninghe watershed.Then the calibrated model was used to calculate the spatial distribution of non-point source pollution.The calculated result indicated that the west part of the watershed was the serious soil erosion area , which is the same as the spatial distribution of organic nitrogen.In one word , the production of non-point source pollution in the west is more than that in the east , while in the south , more than that in the north.The measures for the prevention of non-point source pollution were presented according to the simulated results.