Four zooplanktonic investigations were carried out from November 2007 to October 2008 in Lake Xiliang.Totally,224 species of zooplankton including 112 species of protozoa, 90 species of rotifer, 15 species of cladocera,and 7 species of copepoda were found.The zooplankton species ranged from 75 to 111,with the lowest value(75) occurring in winter,and the highest one (111) in autumn.The density of zooplankton was the highest in winter(126731ind./L),and the lowest in spring(71356ind./L).The densities of zooplankton in summer and autumn were 109743ind./L and 107650ind./L,respectively,and the abundance of protozoa and rotifer were on predominance.The structure of zooplankton community was analyzed in relation to water quality pa-rameters by canonical correspondence analysis(CCA).Temperature,pH,water depth,and the concentrations of TP,COD and DO were strongly correlated with the zooplankton community structure.The parameters that demonstrated a strong correlation with the zooplankton community structure differed among seasons, suggesting that the seasonal variations of zooplankton community struc-ture were related closely to both the water temperature and water trophic status in Lake Xiliang.