It is absolutely necessary to quantify the hydrological processes in earth surface by numerical models in the cold regions of Northwest China, where the runoff generation processes and total runoff amount changes apparently. Hydrological models became major tools for studying the hydrological cycle. However, these models have not considered the frozen soil or glacier hydrology, so they can not satisfy the hydrological process modeling in cold regions. The first purpose of this study is to couple energy balance and mass balance algorithm to the VIC model for improving model effect in cold and mountainous catchments. The improved VIC model simulations were performed in a large mountainous catchment in Aksu River basin in Northwest China. The modeled result showed a good agreement with the observed data. Based on the modeling hydrological data, the runoff components and their response to climate change were analyzed. It is found that: 1) Glacial meltwater recharged 29.2% of runoff for Toxkan River while 58.7% for Kumarik Like River. 2) The annual runoff of the two branch of Aksu River showed an increasing trend, with an increase of about 43.1% for Toxkan River (increased by about 25.95×10⁶ m³·a^-1) and 13.1% for  Kumarik Like River (increased by about 14.09×10⁶ m³ ·a^-1) during the late 38 years, respectively. 3) The total runoff increasing in Toxkan River catchment (a smaller glaciation catchment) was entirely due to non-glacial runoff. The total runoff increasing in Kunmalike River catchment was result from both glacial runoff and increasing non-glacial runoff, of which 42% was from glacial runoff and 58% was from non-glacial runoff.