Abstract: There are three large in terior river systems in the west of Yellow River of Gansu. That is Shiyang river system, Heihe river system and Shuli river system. Considering this case, we divide the Hexi into three areas, I, II and III , through resulting the administrative areas. To these atea, according to the statistic data of the every prefecture and city, we have simulated the increasing velocities of the water quantity used by agriculture, industry, animal husbandry, environment and others, in I, II, and III ares respectively. And on the basis of the study of agriculure using water, we analyse comprehensively the total water used and the water quantity used by every trades.