【Objective】The response of runoff to future climate change was analyzed in the upstream generation area of Shiyang River basin,which is a typical arid basin in northwest China,to provide information for future planning and utilization of water resources in the basin.【Method】Variable infiltration capacity(VIC)model was applied to simulate the hydrological cycle in this basin.Based on parameters calibration, projected climate data under A2and B2scenarios produced with HadCM3 of global climate models(GCMs)was downscaled using statistical downscaling model(SDSM).Different meteorological elements from A2and B2scenarios were analyzed in the upstream generation area of Shiyang River basin,and the projected scenarios were chosen as the input data for verified VIC model to simulate the influence of future climate change on runoff,to analyze the response of runoff to futrue climate change in Shiyang River basin.【Result】The hydrological cycle in Shiyang River basin was well described by VIC model with efficiency coefficients of 0.769and 0.690and correlation coefficients of 0.955and 0.894 in calibration and verification periods,respectively.Average maximum temperatures in 2020s and 2050 sunder A2 scenario were 1.3 and 2.8℃higher than current status,and the temperatures would rise by 1.3℃and 2.5℃in these two periods under B2scenario.Average minimum temperatures would rise by about 0.1℃in the two periods under either A2or B2.Precipitation would reduce by 7.6% and 15.2%in the 2020s and 2050sunder A2 scenario compared to current status,and reduce by 8.7%and 13.1%under B2 scenario.Runoff would decrease by 2.8% and 1.4%in 2020sunder A2 and B2 scenarios and by 13.2%and 8.3%in 2050sunder A2 and B2 scenarios,respectively.【Conclusion】The runoff in Shiyang River basin would reduce in different future periods under A2and B2scenarios.