To utilize biomanipulation technique in eutrophication control of Dianshan Lake,the dynamics of zooplankton community structure including species composition,population dynamics,and standing crop were investigated in Dianshan Lake from January 2005 to December 2006.One hundred and twenty eight species of zooplankton were found,of which 29 species of 23 genera were Protozoa,51 species of 23 genera were Rotifera,33 species of 15 genera were Cladocera and 15 species were Copepoda.The annual average density of zooplankton was 6 965 ind/L,and protozoa and rotifera was accounted for 62.19% and 36.77% respectively,peaked in spring;the annual average biomass of zooplankton was 6.00 mg/L,dominated by rotifera(51.65%) and cladocera(38.38%),peaked in summer.The diversity index H′ of each zooplankton community had a significant positive correlation with its evenness index J and protozoa diversity index H′ showed a significant negative correlation with its density.Based on zooplankton density and dominant species composition,it indicated that Dianshan Lake was in eutrophication status.And the diversity index of protozoa has a good indication of water quality.