By considering the three objectives of ecology,economy,and society in soil and water conservation,the two principles of guaranteeing regional grain self2sufficiency and increasing vegetation coverage,as well as the current status of soil and water loss in the Chaohe River basin in 2005,the three allocation plans of food grain security plan,eco2priority plan,and comprehensive plan are established,as soil and water conservation measures.Impacts of the three allocation plans for soil and water conservation on annual runoff of the Chaohe River are simulated and analyzed based on the water reduction norm of level terraces and forest-lands under different precipitation schedules.Results show that if all the soil erosion areas are converted to artificial woodland,the impact to annual runoff reduction is greater,with the reductions in wet year,normal year,and dry year being 8.27 %,8.28 %,and 11.13 % of the annual average runoff,respectively.Adopting comprehensive allocation plan may affect annual runoff greatly and the reductions in wet year,normal year,and dry year are 11.42 %,8.38 %,and 13.21 % of the annual average runoff,respectively.The impact of grain security allocation plan on annual runoff reduction is littler and the reductions are 7.59 %,6.03 %,and 9.11 % of the mean annual runoff during wet year,normal year,and dry year,respectively.