Abstract: An interactional optimization model of multi-objectives and multi steps is used to calculate the carrying capacity of eco-environments related to water,and determine the course change of the carrying capacity in the case of the water supply of “South-to-North Water”. Transfer Project,the economical normal development and the graduall amelioration of eco-environments.The results are as follows ①Haihe River basin is now in a serious over loading state of eco-environments.Haihe River basins will not reach a good eco-environmental state and,at the same time,not reach a good social and economical state until 2033.②in 2033,when the eco-environments is in a loadable state,the population wil amout to 157.30 millions,6.30 millions more than the natural increasing population of 151 00 millions and the optimal proportion of water use will be 28%, 43%,18% and 11% in industry,agriculture,ecology and life,respectively.