he Hexi corridor is one of the main economic regions in Gansu Province. The scale of economic development of the Hexi corridor in the future depends considerably on the carrying capacity of the water resource in the region. On the basis of the balance principle of water quantity this paper analyses and calculates the balance between supply and demand of water resource, the balance between the water resource and the land resource, and the potential of the carrying capacity of water resource for agriculture development in the Hexi corridor. Meanwhile the corresponding mathematical models are set up. The potential of water resource in the Hexi corridor is great. This potential can brought into play step by step only under the following conditions, namely, develo ping the agriculture of the saving water type and using the water resource rationally and efficiently.