Abstract: Based on the water resources of the Shiyang, Heihe and Shule riverbasins in the Hexi Corridor and their original runoff volume, the actual annual waterresources in the oasis of every county and town of the Hexi Corridor are calculated indetail. From the point of view of ecological balance, the ecological water requirementin oasis and farmland in this region are determined. Then, to basically keep the natural ecological balance of every county and town, the proper oasis area and farmlandarea are given.