On the basis of discerning the natural ecosystem of Wuxi City,in this paper,the ecosystem is divided into four major types: forest,wetland,river and lake,and farmland.What's more,looking from the service functions of natural ecosystem,it also makes the idea of natural ecological assets enter the strategic decision of Wuxi City development,through assessing the economic value quantitatively for the four types of systems and showing different service functional abilities of ecosystem in the form of monetary value,so that it gives the Wuxi City an important guidance for its sustainable development