Abstract: In order to understand the community characteristics of zooplankton and relationships with environmental factors, and aimed to use zooplankton community parameters monitoring the water quality of water source reservoirs, a seasonal investigation was conducted on the water quality parameters, abundance and biomass of zooplankton in water source reservoirs (K1— K10) from January, 2014 to October, 2016 in Zhejiang Province. The relationships and action mechanism between water environment factors and zooplankton abundance and biomass were studied by the method of multiple stepwise regression and path analysis. The results showed that the average abundance of zooplankton in the reservoirs was 97.5 ind./L from 2014 to 2016, mainly composed of copepods nauplii (36.3%), Rotifer (28.4%) and Cyclops (20.0%). The average biomass was 289.3 μg/L, which was mainly composed of Cladocera (39.3%), Cyclops (29.0%) and Cyclops (14.5%). Chl. a content was the decisive factor of zooplankton abundance in spring and summer, and TP content was the limiting factor for fluctuation of community abundance in autumn and winter, and the community abundance was affected by TN through N﹕P ratio in spring. DO content was a decisive factor in the development of zooplankton biomass in winter and summer, and the community biomass was promoted by DO through reducing N﹕P ratio in winter. The present zooplankton stock in the reservoirs was affected by the fluctuation of TP content, the change of N﹕P ratio and the Chl.a content of the water body ultimately reflected.