Abstract: Based on water samples of 30 stations collected in and near Zhao’an Bay in summer（August）and autumn (October) 2015, the species composition，abundance and diversity of zooplankton were studied．A total of 103 species of zooplankton and 24 species/assemblages of planktonic larvae were identified. Copepods were the most abundant species. The dominant species included 14 species of zooplankton.Temora turbinate , Oikopleura dioica and Pavocalanus crassirostris were the important dominant species. The most of zooplankton ecological groups were warm water coastal group and widely distributed off the coastal group. The average density of zooplankton was 761 ind/m³ and 81 ind/m³ and the average biomass was 237 mg/m³ and 52 mg/m³ in summer and autumn, respectively The zooplankton species，density, biomass and variation were much higher in summer than in autumn. The zooplankton species，density，biomass and variation in the outer bay were generally higher than in the inner bay in summer. The zooplankton species，density and variation in the bay opening were generally higher than in the inner bay in autumn. Horizontal distribution of zooplankton species and density showed an increasing trend from inner to outer bay in summer and autumn. The average Shannon-Weaver index was 2.46 and 3.14 in summer and autumn, respectively. Compared with historical data, the zooplankton species number and density in this survey were much higher. However, the average biomass declined significantly.