Abstract: The concepts of effects of soil and water conservation on water resources and water environment were put forward.Using the distributed hydrological model based on physical mechanism(WEP-L),taking the key area of soil erosion control in the Yellow River Basin-the area between Hekou and Longmen towns as a case,the effect of soil and water conservation on water resources is quantitatively studied.The research results indicated: soil and water conservation enables absolute and relative amount of broad sense water resources increased by 7.26 billion m³ and 27.1% respectively,and makes absolute and relative amount of narrow sense water resources decreased by 0.90 billion m³ and 14.4% respectively;soil and water conservation changes the composition of narrow sense water resources,that is the amount of surface water resources decreased,the amount of unrepea ted water resources and ground water resources increased.With the area of Beijing Municipality as a case the water environment effects of regional comprehensive control of soil erosion were quantitatively analyzed.The research results indicated: soil and water conservation measures are important means to control nonpoint source contamination,protect water source quality and ensure drinking water security.