Abstract: This paper deals with the quantitative and biomass dynamics of six submerged macrophyte populations in Manjiang region, Liangzi Lake from March 1997 to March 1998. In the submerged macrophytes community, the dominant species were Potamogeton maackianus, Ceratophyllum demersum, Myriophyllum spicatum. The maximum densities and biomass of six populations appeared in different months within the growing season. The biomass varied with the densities. After the growth season, P.maackianus population and M. spicatum population tended to increase continuously, but that of C. demersum, Vallisneria spiralis and Hydrilla verticillata could develop steadily, and P. crispus population had a tendency of decreasing. The maximum biomass of submerged macrophytes community reached 4676g/m2 (fresh weight, in Oct.), and the maximum density was 1865 branch/m2 (in Nov.). Annual quantitaive dynamics were modelled for six macrophytes both seperatedly and totally by using data from March 1997 to December 1997.