Abstract: To understand the effect of Green tide (Ulva prolifera) on marco and mesozooplankton communities, 4 voyages of comprehensive ecological survey were conducted from May to August 2018 in the sea area near Dingzi Bay, the Yellow Sea (Haiyang, Shandong). The result showed that a total of 57 zooplankton species belonged to 9 taxa. During 4 cruises the number of zooplankton species, the abundance and diversity were consistent, showing the change trend of reaching the maximum at the outbreak stage and the lowest at the late extinction stage. The first dominant taxa underwent the succession process of copepods, pelagic larvae and copepods. The replacement rates of dominant species were 81%, 47% and 88% respectively during 4 voyages. Three communites were differentiated for the zooplankton by cluster analysis. Community I represented the early stage, Community II represented the outbreak and extinction stage, and Community III represented the late extinction stage. RDA test showed that inorganic nitrogen and pH were respectively negatively and positively correlated with the structure of zooplankton communities, especially for copepods; other environmental parameters such as temperature, salinity, dissolved oxygen and so on had weak impact on zooplankton community.