Abstract: In this paper, by means of an analysis on the relationship between streamflow and precipitation in Altay Mountainous Region, the most important points about them can be summarized as follows: (a) the distribution of precipitation: In pediment, the amount of snowfall is about 30% of total annual precipitation and the snowcover occurs in the middle of October or later. In the middle mountain zone with altitude of 2700m, the snow fall amount rises to 50% of its annual streamflow and its snowcover starts to form in the early October. The maximum thickness of snowcover is more than 2 meters in its western part. Therefore, the snowmelt water is an important replenishment of the stream in the region which has 41% of annual streamflow. (b) the seasonal variation of streamflow: The spring runoff is more than the autumn one. Conversely, the autumn runoff in the northern slope of Tian Shan and Qilian Shan is more than the spring one which causes spring drought in these areas.