Freshwater resources are the material basis for human subsistence and economic and social development. The problem of water resources is very severe in the process of development in the northwestern region of China. This paper further discusses the problem concerning the implementation of the uprinciple of harmonious co-existence of man and nature” during the development of the northwestern region, and suggests that in the process of exploitation and utilization of water resources in the northwestern region it is necessary to consider issues from the fact that the region has only a small total amount of water resource but very large annual evaporation and very small annual precipitation. Efforts should be made to broaden sources of water and economize on water, prevent various kinds of waste of water resources, raise the effectiveness of water use, reduce water pollution, recover water resources and improve the environment. It is advisable to take actively the way of “storing water under the ground”，expanding groundwater and developing groundwater rationally, and meanwhile to adhere to expanding usable freshwater resources continuously.