Abstract: The species composition, vegetation type and biomass of the aquatic vegetation and its effects on fishery and lake silt were discussed in this paper. Small Xingkai lake is in the old stage of development. There are about 56 species of vascular plants belonging to 24 families. The dominant species are Potamogewn crispus, Nymphoides peltata, Phragmitis communis and Zizania caduciflora. The vegetation can be classified into the emergent subtype, the floating-leaved subtype and the submergent subtype, including 12 main plant associations. The total biomass (wet) of vascular plants in the lake is about 196 380 tons. The biomass of emergent plants is about 88 950 tons, that of submergent plants about 58 500 tons and that of floating-leaved plants about 48 300 tons. The estimated potential annual production of herbivorous fish is 78.75 tons. During the last 20 years, due to the abundant growth of aquatic plants, the depth of silt in Small Xingkai Lake has increased by 17cm, and water surface decreased by about 1 000 hectares. In order to slow down the silt accumulation, wild aquatic plants should be controlled by rearing herbivorous fishes and introducing economic aquatic plants.