In this paper,the volumes and utilization actuality of available water resources in three main stream systems of the continental drainage basins in the Hexi Corridor are systematically analyzed and estimated by calculating the ecological water demands in the middle and lower reaches based on the state technical specifications for estimating available water resources.The results show that the exploitation and utilization of water resources in the Hexi Corridor are much higher than the volumes of available water resources,especially in the Shiyang River Basin,Heihe River Basin and Shule River Basin,where the volumes of available water resources are 1.519×109 m3,2.140×109 m3 and 1.005×109 m3,but the degrees of exploitation and utilization of water resources in these three drainage basins in 2000 were as high as 149.1%,93.8% and 72.1%,respectively,and they were much higher than the international upper limit of 60%.Thus,many social and ecological crises occur in these drainage basins.Therefore,it is very important to guide the rational redistribution,exploitation and utilization of water resources and achieve scientific management of the drainage basins based on the volumes of available water resources.