Abstract: In 4 cruises carried out in Shenhu Bay fom August to September in 2014,the variation of zooplanktoncommunity structure was studied aimed at the abundance wariations of jellyfish Cyanea purpurea and Aequorea spp.A total of 91 zooplankton species and 20 groups of pelagic larvaein 15 groups and 7 phyla were indentified.Cope-pod was the most dominant group.The density of zoplankton was ranged from 106.85 to281.79 ind./m³.Thedominant species were Subencalanus subecrassus,Sagitta bedoti,Sagitta enflata and Lacifer hanseni et al.The areaofhigh density giant jellyfish was very close to the area of high abundan zooplankton in the bay opening.Followingthe disappearance of macmjellyfish zooplankton abundance increased substantially.It suggested that the appear-ance macro-jellyfish has changed the zooplankton community structure since the fommer was not local species.