Snow is an important part of water resources in arid regions. Change of precipitation pattern and snow melting caused by climate warming are bound to have an important impact on the runoff process and its components. In this study, Hutubi river basin on the north slope of Tianshan mountains was selected as a typical watershed for snow replenishment in arid region. We used site meteorological observation data and IPCC CMIP5 climate scenario data to drive the improved VIC model of rain and snow partition scheme and snowmelt runoff calculation module, and used observed runoff and MODIS snow cover area data to optimize the model's multi-objective parameters. Then the runoff components, runoff variation characteristics and response mechanism of streamflow to climate change were quantitatively analyzed in Hutubi river basin. The results showed that:(1) The runoff process of the Hutubi river showed a concentrated unimodal distribution in the warm season. Snowmelt runoff, rainfall runoff and glacier runoff accounted for 27.7%, 66.1% and 6.2% of the total runoff, respectively. From 1978 to 2010, under the background of significant increase in temperature and precipitation, little change in snowfall amount, and significant decrease in snowfall proportion, the total runoff and rainfall runoff increased significantly, while snowmelt runoff increased slightly. (2) Under the RCP4.5 climate scenario, it predicts that the temperature in the Hutubi River Basin will increase significantly in the future, precipitation will increase slowly, and snowfall will decrease significantly. Affected by climate change, the total runoff of the basin will increase slowly, in which rainfall runoff will increase significantly, and snowmelt runoff will decrease significantly. The annual distribution of runoff will also change in the future, which will show the decrease of spring runoff amount and peak value, the increase of runoff in dry season and the advance of snowmelt runoff peak. (3) In spring, the proportion of snowmelt runoff is the highest, and its change directly determines the change of total runoff. It estimates that a significant reduction in snowmelt runoff in the future will result in a decrease in total runoff during the irrigation period from March to June, which will further aggravate the contradiction of agricultural irrigation water under the existing agricultural mode.