Ecology of zooplankton community, including dominant species composition, density, biomass, and regression analysis amomg zooplankton biomass and the water quality factors were studied at four sampling stations (Ⅰ-Ⅳ) of the West Lake, Hangzhou, a shallow eutrophic lake.After dredging, Tintinnopsis sp., which was the first dominant species of Protozoa replaced by Tintinnidium sp., and Trichocerca pusilla replaced by Polyarthra trigla at stations Ⅲ-Ⅳ.Diaphanosoma leuchtenbergianum, which was the first dominant species of Cladocera replaced by Bosmina longirostris at Station Ⅰ and by Moina micrura at Station Ⅲ.Thermocyclops dybowskii dominated the Cyclopida, and Sinocalanus dorrii dominated the Calanoida after dredging.The annual average density of zooplankton increased 80.5%, of which 57.3% was contributed by protozoans.And the annual average biomass of zooplankton increased 49.7%, of which 36.5% was contributed by rotifers.There had a positive linear relationship between biomass of zooplankton and Chlorophyll-a, COD_Mn and total phosphorus content in the West Lake, Hangzhou after dredging.The relative degrees of the biomass and environmental factors were differed in each sampling station of the West Lake with an order of: Ⅳ>Ⅲ>Ⅰ>Ⅱ.The influence degrees of environmental factors on zooplankton was coincidence with appearance of dominant species changes.The relative degrees of the biomass and environmental factors were differed in each group of zooplankton with an order of: Cladocera>Rotifer>Copepoda>Protozoa.