Abstract: As a nature wetland preservation region,plant resources in Shengjin Lake is richness.The plant communities of Shengjin Lake were investigated in 2006-2007.There are 125 vascular plant species belonging to 94 genera in 43 families.And a new variant Polygonum jucundum var.routundum Z.Z.Zhou et Q.Y.Sun was discribed.Three types of plant communities in lake beach(i.e.Ass.Carex brownii+Carex argyi,Ass.Polygonum jucundum var.routundum and Ass.Polygonum cripolitanum)and 7 types of hydrophyte communities in water body(that is Ass.Zizania caduciflora,Ass.Trpa sp.,Ass.Euryale ferox,Ass.Potamogeton crispus,Ass.Ceratophyllum demersum,Ass.Myriophyllum spicatum+Ceratophyllum demersum,Ass.Myriophyllum spicatum+Vallisneria natans+Ottelia alismoides)were found.At present,the coverage of hydrophyte communities is 30% in Shengjin Lake.Comparison of vegetation types and contribution from different period indicated that the coverage of wetland vegetation was decreasing with development of aquaculture.It concludes that protecting wetland vegetation is very important for ecosystem stability of Shengjin Lake.