By using the raster data of landuse and soil types

this paper builds a raster-based SCS model

which in turn enables the improved model to make a better consideration of the heterogeneity of watershed underlying surface and the heterogeneity of rainfall. In addition

this paper applies the new model in a real watershed

result from which shows that simulation accuracy can be significantly improved by the raster-based SCS model

compared with the original SCS model. Among the 44 rainfall events in total

the number of the rainfall with a runoff simulation accuracy of above 85% increases from 12 to 26. What's more

runoff distribution maps are obtained using the improved model

which help provide more accurate runoff information on the water management of watershed.