Abstract: Based on the data obtained from four voyages in February (winter), July (summer), November (autumn) in 2015 and April (spring) in 2016, we investigated the structure of zooplankton community, including species composition, abundance, biomass, dominant species and species diversity in Hailing Bay. A total of 132 zooplankton species and 14 types of pelagic larvae were identified. The most dominant group of zooplankton was Copepoda (54 species). There was no similar dominant species between two adjacent seasons, indicating that the zooplankton community in Hailing Bay had obvious seasonal variation. Abundance and biomass of zooplankton were highest in winter but lowest in summer. Zooplankton abundance was greater in autumn and spring than in winter and summer except for Noctiluca scintillans. Both Shannon-Wiener diversity index (H′) and Pielou's evenness index (J′) were higher in autumn and summer than in winter and spring. N. scintillans appeared in winter and spring with mass propagation since the temperature was low, but disappeared in summer and autumn. Correlation analysis shows that there is a significant negative correlation between N. scintillans-dominated Protozoa and water temperature, indicating that water temperature is one of the main factors affecting the growth and reproduction of N. scintillans in Hailing Bay.