Dishui Lake is the largest artificial lake in Shanghai, China. Water in the lake comes from the Huangpu River via the Dazhi River through surrounding river networks, accepts surface runoff and passes through a sluice into the East China Sea. The lake is important for flood control, drainage, water replacement and other functions, and is critical to the Lin'gang New District's landscape and to Shanghai's eco-city construction. It is a newly formed lake with a fragile ecosystem and could easily be affected by external pollutant sources. Zooplankton play an important role in lake ecosystems and biological productivity at the base of the food chain since they eat phytoplankton, bacteria and detritus and provide food for fish and other aquatic organisms. Filter-feeding fish were put into the lake in recent years to control phytoplankton numbers, but a growing filter-feeding fish population could harm the zooplankton community. Consequently, long-term monitoring of variation in the zooplankton community is vital to the health of Dishui Lake. In order to explore the relationship between zooplankton community structure and environmental factors in Dishui Lake, we investigated the species composition, density and biomass distribution, dominant species of zooplankton and water quality parameters in Dishui Lake. We used eight sampling sites and took samples monthly from January to December, 2012. We identified 61 species belonging to 33 genera, including 45 Rotifera belonging to 22 genera, 7 Cladocera belonging to 4 genera and 9 Copepoda belonging to 7 genera., Dominant species included Copepoda species Limnoithona sinensis and nauplii, ten Rotifera species, while Cladocera had no dominant species. Dominant species were different in each season. The annual average density of zooplankton was 1200 ind./L and the annual average biomass was 1.67mg/L. Zooplankton species number, density and biomass were all higher in spring and summer than in autumn and winter. The annual average of Shannon-Wiener and Margalef diversity indices were 1.61 and 1.01 respectively. Both of these diversity indices were significantly different in different seasons, but not significantly different between the eight sampling sites. Pearson Correlation analysis, Multiple Regression Analysis and Redundancy analysis (RDA) of species number, density and biomass of zooplankton and environmental factors displayed a significant relationship between zooplankton community and environmental factors. This indicated that the seasonal variation of zooplankton community structures in Dishui Lake was closely related to the water eutrophication status. Water temperature was a key factor in variation in the zooplankton community structure, and chlorophyll a, pH, total nitrogen (TN) and total phosphorus (TP) were also important factors. Zooplankton species number, density and biomass increased with a rise in water temperature and a decline in pH. TN increased the density and biomass, but excess TP tended to reduce the number of species present. Several methods were used to assess the water quality and eutrophication levels. Results showed that the water quality status of Dishui Lake in 2012 could be classified as α-mesosaprobic and its eutrophication level was at semi-eutrophic levels under a comprehensive application of the water quality index, trophic level index (TLI) and diversity indices assessment methods.