Abstract: Off-site identification of wetlands is a useful screening tool for determining the possible existence of wetlands. However, on site verification is necessary in establishing the existence, size, shape, and type of wetlands. The main indicators of the presence of wetlands are hydrophytes, hydrology, and hydric soils. A new technique for identifying wetlands on Landsat TM imageries was developed in this study. With this technique, more attention was placed upon recognition of highly vegetated areas or water bodies, for these rendered higher potential for being wetlands. Results were evaluated with existing data such as topographical maps, aerial photographs and ground truthing. Two methods were used to classify pixels into different categories:supervised and unsupervised classification. Results have indicated that, there are so many wetlands in the study area, which have been neither identified nor given special protection. They include riverine, lacustrine and palustrine wetlands. Various vegetation types dominated by Cyperaceae and Juncaceae characterize the marshes. As a result of the constraints imposed by the resolution of the imagery, wetlands over 1 hm² in size could be detected with 90% accuracy, but those under that threshold could generally not be detected. Research has shown that an object must be 54 m across before its radiance can be accurately detected, thus indicating that the minimum size of a detectable object is larger than the 30 m resolution of Landsat imagery. This paper aimed at applying Landsat TM data as an off site technique for identifying wetlands in the Fuxin area, China.