As one of the large ecological infrastructures, urban water system connectivity project is an important part of urban ecosystem construction. It has a variety of effects, such as conserving biodiversity, enriching urban landscape and increasing land value. It is helpful for the scienti c planning and construction of the project to systematically evaluate the effects. However, due to the complex and various effects of urban water system connectivity project, there is no complete effect system and quantitative method. In this paper, the composition and mechanism of positive and negative effects of ecological economics of urban water system connectivity project were deeply analyzed to improve the composition system of eco-economic effects. At the same time, the emergy theory was used to put forward the quanti cation method of ecoeconomic effect system. Taking the urban water system connectivity project in Xuchang as an example, it's ecological, social and economic effects were evaluated. The result showed that the average eco-economic effect of the project is 57.8 million dollars/year. Economic effect and ecological effect are signi cant, accounting for 88.83% and 9.77% of total effect, respectively. The former is mainly due to land value increment, and the latter is principally owing to biodiversity conservation. It showed that the water system connectivity project in Xuchang can promote the economic development of the surrounding areas and create a good ecological environment, which will bring huge eco-economic effect to the region.