Taking Manas river basin as the research area,using the method of mathematical statistics and based on the available hydrological and meteorological data from 1958 to 1987, the paper analyzed the tendency change and the effect of global climate change on precipitation, temperature, snowmelt runoff. It established digital hydrological model based on Xinanjiang model and simulated snowmelt runoff in 1981. Using the model and assuming the different climate scenarios, it analyzed the impact of snowmelt runoff on climatic change sensitivity in arctic-alpine mountain area.