Abstract: Based on the data collected in the offshore area of Fengxian during the spring tide and neap tide in November 2009, we analyzed the species composition, biological density, biomass distribution, biodiversity and ecological characteristics of dominate species of zooplankton. Results show that the zooplankton density during spring tide is higher than that during neap tide, while the number of zooplankton species, biomass and biodiversity during spring tide are less than those during neap tide. The dominance (Y≥0.02) of Labidocera euchaeta and Schmackeria poplesia and their proportion of species number during spring tide are higher than those during neap tide, while Tortanus vermiculus shows an opposite result. Marine zooplanktons have strong ecological response to tidal variation.