Abstract: From Dec. 2008 to Sep. 2009, we studied the characteristics of community structure of zooplankton in a tropical urban reservoir, Shenzhen Tiegang Reservoir.Seventy-three tropical, subtropical or eurythermal species of zooplankton are identified, and Rotaria ranks first in terms of species number and quantity at each sampling site in every sampling season. Tintinnidium fluviatile, Polyarthra dolichoptera, Brachionus angularis, B.falcatus, Asplanchna priodonta, B.calyciflorus and Copepodities are the main dominant species (groups) in4 seasons. The clustering and nMDS ordination analyses reveal significant difference of spatial distribution among the community structures of zooplankton. Jiuwei Bay and Liaokeng Bay belong to a same group in 4seasons, and B.calyciflorus, Keratella quadrata and B.caudatus are classified in this group. B.falcatus is mainly distributed at Xili inlet, while B.forficula and Gastropus hyptopus are mainly distributed in the centre of the reservoir. According to the analyses of the density, dominant species (groups) composition and diversity indices of zooplankton, the water in Tiegang Reservoir has been affected by human activities, and Jiuwei and Liaokeng Bay are relatively seriously affected.