Taking Yellow River Source Region as a study area, this paper simulated and estimated the runoff processes under the different climate and land cover change scenarios using distributed hydrnlogical model--SWAT. Owing to the particular convergence condition in YRSR, the model calibration intensified the parameters on snowmeh and soil temperature. The evaluation of the resuits showed that SWAT simulated the hydrological process comparatively well. The runoff estimting results under different scenarios are believable and useful in practice to some extent and SWAT will play a more important role in the cold region water resources research and management with more edfining the structure and parameters of the model.