Since the small watershed within city is an important part of urban ecosystem,the rational planning and comprehensive harness of these small watershed within city are important way to prevent water and soil loss and to facilitate sustainable development of the city.The Qing shui stream flows through the urban area of Chongqing city,and it has the problems such as heavy pollutions and environment deterioration, which becomes the barriers of city development.Based on the definition of the conception of the small watershed within city,the comprehensive harness and environmental benefits are analysis.The result shows that the small watershed within city should be repaired by the way of ecosystem renovation,and the benefits analysis should be taken in the aspects of eco-logy,economy and society.