Abstract: In order to understand the size diversities of the zooplankton community and response characteristics of the comprehensive water bodies by trophic level index (TLIc value), a seasonal investigation was conducted on zooplankton size diversities from two types of 16 drinking water sources (H1-H8 for rivers, K1-K8 for reservoirs) from January to October 2011 in Zhejiang Province. The results showed that seasonal variations in the biovolume density of zoo-plankton from high to low were January (0.681 mL/L), April (0.443 mL/L), October (0.252 mL/L), and July (0.229 mL/L). The first dominant species of January, April, July, and October were Sinocalanus dorrii, Asplanchna sp., Thermocyclops dybowskii, and Bosmina longirostris respectively. Zooplankton were mainly Rotifera (44.6%) and Cladocera (23.4%) in the rivers by their biological volume, while Calanoida (39.5%) and Rotifera (29.0%) in the reservoirs. There were significant relationships between lg 10 transformed zooplankton/phytoplankton biomass ratiolg (ZB:PB) and size diversi-ties (P < 0.01) or species diversities (P < 0.05) of zooplankton in the drinking water sources during summer and autumn, and crustacean zooplankton size diversity index was significantly positive correlated with lg (ZB:PB) (R²=0.77) in the reservoirs. Crustaceans size diversity (P < 0.01) were more reliable to TLIc value of the rivers than the species diversity during summer and autumn, supported by the useful information amplification from the numbers of crustaceans (ind./L) converting into biovolume density (mL/L).