To clarify the community structure and seasonal changes of surface zooplankton in the north shore of Hangzhou Bay,as well as the relationship with environmental factors, zooplankton were collected at 10 stations in the north area(121°45'-122°09'E,30°45'-30°51'N)by a larvae net (130 cm mouth-diameter,0.5 mm mesh-aperture) during the spring tide each month in August and November 2014,February and May 2015. In this research, a total of 42 species were collected, of which 10 were dominant species. 7 dominant species were identified in Autumn(the most) and 4 dominant species were identified in summer (the least). However, only Labidocera euchaeta, Pseudodiaptomus poplesia and Tortanus vermiculus were the common dominant species in four seasons. The highest mean biomass and abundance of zooplankton were in summer and the lowest were in winter. The results indicated the zooplankton in the north shore of Hangzhou Bay could be divided into four ecotypes:freshwater group,estuarine group, inshore low salinity group and eurytopic group. The analysis from SPSS showed that the seasonal changes of zooplankton community were obviously affected by salinity, water temperature, Chl.a and DO.However, water temperature and salinity were the two key factors for community structure.