Water is an essential resource for human existence. It is also the basis of production and living. However the water resource is unbalanced both in time and space and used in low rate, which has become very important factors to restrict the sustainable development in each district at present. The selected research area—Changning County is in a period of rapid economic development, and the water resources carrying capacity will affect the development. The article summarizes the other titles and applies the actual survey data to analyze the water resources carrying capacity. It shows that the water resources carrying capacity in Changning County is adapting to the present economic and social development, but will be insufficient in long term. So it should coordinate the relationship between human and nature to promote the sustainable development of Changning County.