Based on such principles as sustainable development and ecological cycle, this paper evaluates the water resources carrying capacity(WCC) of Changchun-Jilin region using a population-economy-water resources correlation evaluation model built on the basis of WCC evaluation method as elaborated in the methodology of Functional Zoning of Population Development. Results show that the annual WCC of Changchun-Jilin region is able to support the population there, as a basic balance is struck between population and water resources. The incorporation of WCC into overall urban planning is one of the building blocks for sustainable city development with an advisable size.