With the intensification of human activities,a lot of hydraulic projects such as reservoirs, dams, levees, flood storage and detention areas have been built,which have completely changed the natural water flow. The soil and water assessment tool (SWAT) was calibrated and verified in the baseline period before 1960s. It simulated the runoff after 1990s with stability human activity.It set up the three circumstances such as natural SWAT, SWAT with just concerning land cover change and SWAT with concerning hydraulic projects activities as well as land cover change. The simulated results of Wudaogou, Yangzishao, Dongfeng and Panshi hydrological station show that the correlation coefficient R2 and Nash coefficient NSE increases from 0.82, 0.56 to 0.91, 0.79. The 91.3% precision of the increase value is due to the role of hydraulic project,and the remainder is caused by the change of underlying surface.The operation of hydraulic project plays a leading role in the runoff change of the basin.