Abstract:We investigated the constitution, abundance and diversity of zooplankton in Niyang River, the branch of the Yarlung Zangbo River, Tibet, based on season from 2008 to 2009, and taken quantitative analysis to study spatio-temporal characteristics of zooplankton and their corresponding to environment using multivariate statistics method.The results were as follows.Firstly, zooplankton community in Niyang River included protozoa, rotifera, cladocera and copepoda, and there are 9 orders 13 family 14 genus for protozoa, 1 order 7 families 17 genus for rotifera, 1 order 1 family 1 genu for cladocera, and 2 orders 2 families 2 genus for copepoda.Among them, protozoa is mainly based on Difflugia and Glaucoma, rotifera is mainly based on Rotaria and Monostyla.Secondly, specie richness and biomass for zooplankton in Niyang River are descending with the elevation.Meanwhile, biomass, the specie richness and total abundance of zooplankton in summer are low, especially for specie richness in summer, which is lower than that in other seasons, although biomass and total abundance are a bit higher than that in winter.Influenced by the stability of water in Niyang River, Shannon-Wiener diversity index and Pielou evenness index, which are lowest in summer followed by winter, are lower at the interchange of river.Total abundance of seasonal succession for protozoa and rotifera in Niyang River are similar, that is, there are two climaxes which appear in spring and autumn respectively and two troughs which appear in summer and winter respectively.Thirdly, using Duncan comparison method to judge the difference among sampling sites and seasons for specie richness, total abundance, Shannon-Wiener diversity index and Pielou evenness index, there is no significant difference among four sampling sites for four indices mentioned above.As for seasons, significant difference only exist between autumn and winter for total abundance, and there is no significant difference among seasons for the rest three indices.Fourthly, based on the CCA method, as for protozoa community, dissolved oxygen has a great influence on the density of Difflugia, total dissolved solids has a great influence on the density of Prorodon, Bursellopsis, Colpoda, Glaucoma, Enchelys, ammoniacal nitrogen has a great influence on the density of Euglypha, as for rotifera community, dissolved oxygen has a great influence on the density of Monostyla,Ascomorpha,Enteroplea,Asplanchnopus, total phosphorus has a great influence on the density of keratella.Last but not least, we predict spatio-temporal character of zooplankton in Niyang River and environment factors based on CART method, the results show that, total abundance of zooplankton is influenced by hardness, season, elevation and substrate of watercourse, Shannon-Wiener diversity index is influenced by alkalinity, season, hardness and water temperature, and Pielou evenness index is influenced by alkalinity, total phosphorus and water temperature.The paper also suggests paying close attention to zooplankton and the environment factors mentioned above owing to their important indication function, in order to warrantee the sustainable development of Niyang River aquatoriumecology.