【英文摘要】The upstream of Heihe River basin in northwestern China, was chose as the study area. We developed the optimized technology for snow mapping for the mountainous region in northwestern China, and then based on the normalized difference topography model, to eliminate the effect of topography and the technology for division between snow and cloud. We describe and validate a new method that retrieves snow-covered area.With this method, the Kappa coefficient and the accuracy of the snow cover area are higher than with MODIS snow cover products. We also describe and validate the C model for mapping fraction of snow cover. The statistical results of mean snow cover, mean absolute error, RMS error and correlation coefficient show the modified C model is better than the S model. The observation data of the meteorological and hydrological stations located in the upstream of Heihe river basin were utilized to analyze the status and the regularity for the climatic change from 1956 to 2008. Snowmelt Runoff Model (SRM) was chose to simulate snowmelt runoff and scenario forecast the change trend of snowmelt runoff in catchment scale for the mountainous region in Northwestern China. The results show that climatic warming was apparent in the upstream of Heihe River basin in the past 50a. Annual average air temperature of three different weather stations located in the basin has increased 2.1℃, 2.6℃ and 2.9℃ respectively. The snowmelt runoff has increased obviously from 1970 to present. With different warming climate scenarios, the results by SRM simulating showed that the first occurred time of snowmelt runoff shift ahead and discharge become larger as responses of snowmelt runoff to air temperature increasing, and the influence of temperature rising on average discharge of the whole snow season is not obvious. On the other hand, simulated discharge showed a marked increase trend with the increase of precipitation. And, the simulated results show that the increase of precipitation almost has no influence on the occurring time of snowmelt runoff.