A study on the classification of wetland landscape ecosystem is the key of landscape mapping. The fundamental rules of wetland landscape mapping classification system were studied first. The main factors which cause difference between landscape ecosystems were further detailed analyzed, and the conclusion is that the main factors are human activities, hydrology, geomorphology and vegetation. Finally, each category of the classification system is that: 1)the extent of human activities as the first class: natural wetland landscape, half natural wetland landscape and artificial wetland landscape; 2)geomorphology as the second class: flood land, depression, valley and terrace; 3)marsh wetland vegetation as the third class, which amalgamated with the way of indistinct assemble classification. Rivers as important wetlands were divided into two types: permanent river and marsh river. The classification system can give good service for landscape patterns, function, ecological planning and reconstruction of wetland in the Sanjiang Plain.