The soil and water assessment tool (SWA T) is a physically-based continuous event hydrologic model. This paper mainly introduces the sensitivity analysis model of the AVSWA T2005 and its verification in Yunzhou Reservoir basin. Based on the sensitivity analysis, the main parameters affecting the simulated values in the watershed are determined. Results show that the CN2, SOL_AWC, and SOL_ K parameters have the most significant influence on the simulated values of runoff from Yunzhou water shed, the sensitivity being in a high level ; and the SLOPE and GWQMN have the more significant influence on runoff, the sensitivity being in a general level . The parameters are adjusted based on the above analyzed results and the model is verified using over 10 years data of monthly runoff . Satisfied simulation results are obtained with the relative error under 15 % and Nash-suttcliffes coefficient (Ens) more t han 0. 7. The simulation result of SWA T model for Yunzhou Reservoir basin is good. Therefore, the application of sensitivity analysis module of SWAT model in t he soil-gravel area of North China may improve the accuracy of simulation dramatically.