Wetlands play a key role in regional and global environments and are critically linked to many major issues such as climate change, water quality, hydrological and carbon cycles, and wildlife habitat and biodiversity. Mapping wetlands and monitoring their change constitute a long-term task. Remote Sensing characteristics with macrocosm, dynamics, quantity, and comparability will largely favor wetland research. The radar remote sensing, which is not affected by climate conditions, has been especially proved to be an effective tool in wetland monitoring. In this paper, the unique polarimetric data of Radarsat-2 were investigated for wetland classification, and the target decomposition was used for optimum characterization of wetland target scattering. It is shown that the polarimetric information provided by Radarsat-2 permits  discriminating eight classes of land surface, and leads to an effective unsupervised and supervised Wishart classification of Poyang Lake wetland. Hence, the combination of Radarsat-2’s polarimetric and all-weather capabilities is likely to provide unique information for operational mapping and monitoring of wetlands.