Abstract: For understanding the zooplankton community structure characteristics and the state of the water quality of the Hongjiannao Lake, and to scientifically protect the desert lake ecological health, an investigation of zooplankton community and water environment in Hongjiannao Lake were conducted from 2016 to 2017, and the seasonal variation trend and influencing factors of zooplankton abundance and diversity were analyzed. A total of 35 zooplankton species belonging to 30 genera were identified. The rotifera were dominant in the species composition, with accounting for 41.6%. The main dominant species were Vorticella microstoma, Notholca labis, Polyphemus pediculus, Moina mongolicaand Sinocalanus dorrii. The seasonal variation of number of species showed a trend of winter > spring > autumn > summer. The annual density of zooplankton ranged from 4.2 to 326.3 L^-1 with an average of 61.9 L^-1, and the annual biomass ranged from 0.001 to 1.138 mg·L^-1 with an average of 0.193 mg·L^-1. There was a seasonal difference in zooplankton abundance, showing the characteristics of summer > autumn > winter > spring. The mean value of Shannon-Weiner diversity index and Pielou evenness index were 2.040 and 0.712, respectively, indicating that the diversity in autumn and winter was higher than that in spring and summer. Canonical correspondence analysis show that water temperature, electrical conductivity and dissolved oxygen were the main environmental factors that significantly affected zooplankton community distribution. According to the biodiversity index and the comprehensive trophic level index, the results show that the water quality was moderately polluted and slightly eutrophicated in Hongjiannao Lake. The control of water quantity and the management of water quality had great influence on the zooplankton community structure. The results of this study can provide a reference for ecological protection and water resources development in Hongjiannao Lake.