Wetlands are among the most important ecosystems on Earth, which provide plenty of ecological services, and supporting the sustained development of the human being. However, with the development of our society and the change of natural conditions, lots of wetlands is degrading and disappearing. According to the conclusion from Millennium Ecosystem Assessment, the degradation speed of wetlands is faster than any other ecosystems. In order to protect wetlands, it is very important to monitoring degradation of wetland and analysis the driving factors resulting in degrading, then recognize the contribution of these factors by turns. Firstly, extracting exactly wetlands from satellite images is the key in this paper. In the hill region, with the help of spatial analyses function in geographical information system software and DEM simulation method, the simulated images of hill shade is gained according to the solar radiation conditions of remote sensing image, then the mixture of hill shade and wetlands in satellite images can be recognized, and influence of hill shade on wetland can be removed successfully. In the flat urban region, because there is the similar digital number scope of old residential areas and wetlands in urban region, the digital number is replaced with surface reflectance to extract urban wetland information, and old residential area influences on the wetland is wiped off. Urban wetland is exactly extracted with normalized difference water index and its change is accurately detected with Landsat TM images acquired at 1991 and 2007. According to the wetland water budget theory, taking hydrology factors in wetland water budget equation as the main index, together with the society, hydrology and meteorology statistic data, this research quantitatively analyzes the contribution of natural and human driving factors to wetland change. Natural factors are the main reasons for wetland change, the decrease of precipitation, surface water inflows and the increase of evaporation are negative contribution to wetland maintenance, about 39.22%, 14.05% and 11.85% respectively, the decrease of surface water outflows is positive contribution, about 12.75%. To the human factors, urban sprawl is negative contribution, about 3.42%, however, technology progress is positive contribution, about 25.55%, and helpful to protect wetland and reduce the negative contribution of urban sprawl.