Non-point source pollution (NSP) from the inland is one of the main factors causing the river pollution and marine eutrophication in coastal zone. By using the long term hydrological impact assessment model(L-THIA), combining the GIS spatial analysis technology and quantitative simuation, the paper analyzed the spatial-temporal distributing characteristics of yearly surface runoff and NSP load caused by land use change. The results indicate that the great losses of agricultural land have resulted in a decrease of total NSP load. The rapid urban growth causing imperious area expansion is the main reason for the higher output runoff and pollution loads in near coastal zone. The variation of the direct runoff and NSP loads is closely related with the pattern of urban growth and land use changes.