The fast urbanization in Chongqing metropolitan has had a great impact on the environment and resources. The water resource has been recognized as one of the key elements to the sustainable development of this region. This paper presents a method of predicting the regional Water Resource Carrying Capacity (WRCC) using the supply-demand balance model. The method predicts that the WRCC of Chongqing metropolitan is from 8.8 million persons to 14 million persons in 2020 and it will not become the bottleneck of the social and economic development of Chongqing Metropolitan in the coming period of time. However the climate change and its impact on the regional ecology will have an effect on it. The results show that the usable capacity of Passing-by water is the most important element of the WRCC of Chongqing metropolitan therefore the protection of the ecological environment in the upstream area is very important. This paper has proposed tangible advice on the sustainable social and economic development in context of water resource.