Taking the Ili Kashi River for a study area, the paper used a distributed SWAT model to simulate runoff process of the basin,and also established the soil, land use, meteorological database witch the model need. It applied the data of monthly runoff from 1990to 1996for the calibration of SWAT model, used the data during the period of 1997to 2000to validate the model, and evaluated the applicability of the model in the west area of Tianshan mountain. After many times of model parameter calibration, the model is capable of simulating hydrological processes in Xinjiang Mountainous. The results show that the relative error of simulation (RE)is 8.6%, and the Nash efficiency coefficient (NSE) is 0.80.Snowmelt plays an important role in the formation of runoff in Xinjiang, The melting snow parameters of the model have greater impact on the simulated runoff results. Therefore, to appropriately adjust the snowmelt parameter values can improve simulation accuracy.