The nutrient relationships of wetland species have been studied in European and American wetlands, but there are few correlative studies in northeast China. We conducted a systematic census of plant nitrogen (N) and phosphorous (P) concentrations and N:P ratios by biomass for 21 characteristic plants of herbaceous marsh wetlands in the Sanjiang Plain, northeast China. Our results showed that compared with European and American correlative studies, the lower N content is the primary characteristic of N and P stoichiometry of wetland plants in this area. Inter- species and Inter-plant groups variation of N, P and N:P ratios were both significant, and the effect of plant groups was stronger than species. the comparative effect of species and habitat showed that the nutrient contents of tissues with respect to N, P, and N:P ratios differed by species, zone and/or the interaction of species and zone. The N content of tissues varied by species, zone and their interactiont. The P content varied by species and zone only. N:P ratios differed by species, but not by zone or the interaction of species and zone. Overall, the study found that species tissue content varies by species and nutrient, and that patterns for specific species and nutrients cannot be generalized between different habitats.