Abstract: To evaluate tropic state and biotic community of Hengshan Reservoir, Zooplankton samples were collected with a plankton net in May (spring), July (summer), October (autumn) 2012 and January (winter) 2013, fixed with 5% formaldehyde, stored in plastic bottles and identified with a microscope. Biodiversity index and physicochemical index were utilized to assess the water quality of Hengshan Reservoir. A total of 100 zooplankton species (47 Protozoa, 36 Rotifera, 12 Cladocera and 5 Copepoda) were identified with the seasonal variation that 66 the zooplankton species were found in summer, 53 species in spring, and 15 species in winter. The dominant species were Anuraeopsis fissa, Polyarthra trigla, Brachionus diversicornis, Trichocerca similis, Tintinnopsis wangi, Tintinnidium fluviatile, Difflugia globulosa and Epistylis lacustris. The results of dominant seasons change rate (R) showed that the R value was the highest in winter-spring (100%), followed by summer-autumn (85.71%) and spring-summer (62.50%), and the lowest in autumn-winter (50.00%). The average annual abundance of the zooplankton was 1460 ind./L, ranged from 17 ind./L to 3164 ind./L, and the highest was in summer (2613 ind./L). The average annual biomass was 1.252 mg/L, ranged from 0.042 mg/L to 2.732 mg/L, and the highest one was in summer (1.728 mg/L). The mean value of Shannon index was 2.06, ranged from 0.88 to 3.21, generally lower in autumn and winter and higher in spring and summer. The annual average of Pielou index was 0.68, ranged from 0.37 to 0.96, the lowest in autumn and maximum in winter. The annual average of Margelef index was 1.30, ranged from 0.51 to 2.24, lower in autumn and winter and higher in spring and summer. According to the comprehensive trophic level index, the values of Hengshan Reservoir were varied from 33.36 to 44.15 with the average of 38.45. These results showed that environmental factor was significantly associated with zooplankton species composition, and the zooplankton community structure of Hengshan Reservoir was much affected by temperature and pH. Water quality evaluation indicated that Hengshan Reservoir was in secondary pollution and meso-trophic level.