Wetlands have the richest biodiversity on the Earth's ecological landscape and are one of the most important environments inhabited by humans; they are one of the world's three major ecosystems (the other two are forests and oceans). Wetlands are regarded as "the Earth's filtration system". China is in the process of rapid urbanization, and many wetlands have been transformed into urban wetlands. Urban wetlands are often the product of urbanized process, which plays an important role in the transformation and migration of pollutants, surface water storage, improving urban water quality and adjusting urban microclimate. Therefore, urban wetlands are widely used in urban ecological construction. Because the urbanized process has a significant impact on the structure and catchment of wetland, the ecological functions of wetlands have changed dramatically. Evaluation of an urban wetland's ecological functions is important to scientifically understand urban wetlands and reasonably utilize and protect urban wetlands. Reference wetlands are specific wetland sites within a region,and they are less disturbed and close to natural wetlands. Taking the typical wetlands in Xian Lin Nanjing as examples, we selected appropriate reference wetlands to evaluate the characteristics and functions of the water environment in urban wetlands by using the hydrogeomorphic method. We used RS(Remote Sensing)、GIS(Geographic Information System) and field investigation to develop a functional index and model for the wetlands. The results showed that:Compared with reference wetlands, the seasonal water level changes of urban wetlands have no regularity. The average annual water quality indicators for the reference wetlands mainly remained at Class Ⅱ water quality standards, and those for the urban wetlands mainly remained at Class Ⅳ water quality standards. The water environment functions of the urban wetlands showed obvious degradation due to urbanization. The WEFI(Water Environment Function Index) score for the urban wetlands declined by 24%. In the sub-index of WEFI, the FCI(Functional Capacity Index) score of the water storage function for the urban wetlands declined by 22%, the FCI score of the water purification function declined by 33%, and the FCI score of the hydrological adjustment function declined by 17%. In addition, the water environment functions of different urban wetlands showed obvious differences because of the impact of the complex urbanized landscape. The quality of water environmental functions of Ji jiabian Wetland is the best, followed by those of Cai yuehu Wetland and Xi huxi Wetland. There has been some degradation of water environment functions in Gui shanju Wetland and Nanyou Wetland. The quality of water environment functions of Nancai Wetland was the worst. Therefore, we can conclude that Ji jiabian Wetland, Cai yuehu Wetland and Xi huxi Wetland, which have good water environment functions, can be regarded as models for reforming wetlands during urbanization. By revealing the differences in water environment functions between the six urban wetlands, not only can we provide a scientific basis for wetland resource conservation and scientific management of urban wetlands but also achieve social, economic, and sustainable development in the city.