Zooplanktonic investigation was carried out from September 2013 to June 2014 in Chaohu Lake and its three tributaries (Zhegao River, Hangbu River, and Nanfei River). Totally, 297 species of zooplankton including 124 species of protozoa, 135 species of rotifer, 29 species of cladocera, and 9 species of copepoda were found. The species number of zooplankton was the highest in Nanfei River (203), and lowest in Chaohu Lake (130). Protozoa and rotifer had the highest species number in Chaohu Lake and three tributaries (Table 2, Appendix). The total abundance of zooplankton was 644 223 ind/L, Zhegao River had the highest abundance, Chaohu Lake had the lowest abundance, and the abundance of protozoa was on predominance. Zhegao River had the highest abundance of zooplankton in four seasons (Fig. 2a). The total biomass of zooplankton was 253.14 mg/L, Nanfei River had the highest biomass, Hangbu River and Chaohu Lake had the lowest biomass (Table 2). Zhegao River had the highest biomass of zooplankton in spring and winter, Nanfei River had the highest biomass of zooplankton in summer and autumn (Fig. 2b). Compared with three tributaries, Chaohu Lake had the lowest species number of dominant species (Table 3). Based on physiochemical parameters, it was found that Chaohu Lake and three rivers were in eutrophic or hypereutrophic status, the degree was as follows: Nanfei River > Chaohu Lake > Zhegao River > Hangbu River (Table 1). Zooplankton community structure was analyzed in relation to physiochemical parameters by redundancy analysis (RDA), the results showed that these was no obvious spatial heterogeneity of zooplankton community structure in Chaohu Lake and its three tributaries in four seasons, and physiochemical parameters were weekly correlated with the zooplankton community structure (Fig. 3).