Zooplankton plays an important role in aquatic ecosystems and biological productivity at the base of the food chain since they eat phytoplankton, bacteria and detritus, and provide food for fish and other aquatic organisms. The community structure and succession of zooplankton are greatly affected by the physical-chemical factors in waters. Knowledge of zooplankton community dynamics and its relationship with environmental factors is crucial in understanding the changes in aquatic ecosystems. Caohai is one of the three Plateau Freshwater Lakes in China, with a good natural location in the Yunnan-Guizhou Plateau, playing an essential part in regional ecosystem balance .However, since the lake was restored in 1982, there have been only two reports published thus far professionally about zooplankton community in Caohai Lake, information of zooplankton community dynamics and its relationship with environmental factors in Caohai seems rather limited. Investigation and research on zooplankton community to fill the lack of information on zooplankton community in Caohai Lake is necessary and urgent. In order to explore the characteristics and long-term changes of zooplankton community structure, status of water quality, and their relationships with environmental factors in Caohai Lake, we investigated the species composition, density, spatial distribution of zooplankton and water quality parameters in Caohai Lake in Summer and Autumn, 2014. There were 151 species identified which belonging to 83 genera, including 60 Protozoa belonging 31 genera, 55 Rotifera belonging to 26 genera, 18 Copepoda belonging 15 genera, and 18 Cladocera belonging 11 genera. Dominant species included 3 Copepoda, 1 Protozoa and 1 Rotifera, the main dominant species was Sinodiaptomus sarsi of Copepoda;The significant spatial heterogeneity environment caused the low Shannon-Wiener diversity index and Margalef richness index, they both were 1.14 and 0.47 respectively. There was a significant variation of zooplankton community in Caohai Lake between Summer and Autumn, species composition changed by 77.5%between the two seasons, and the zooplankton density in Summer was higher than it in Autumn,the average density of zooplankton were 1 505.53 and 506.60 ind·L-1 respectively, and the annual average was 1 006.09 ind·L-1. The research also showed that the water quality status of Caohai Lake in 2014 was Mesotropher-Moderately Polluted under application both trophic level index and zooplankton community parameters. Compared with the historical period, the change of zooplankton species is small, but abundance is greatly reduced, dominant species have also been severe changed, this may be associated with the degradation of Caohai Lake water quality, but the specific ecological processes and drive mechanism still needs further research and long-term monitoring.%由于处于食物链的中间位置，浮游动物在水生生态系统中起着至关重要的作用，其群落特征、动态演替等很大程度上受到水体理化因子的性质和相互作用的影响；研究浮游动物群落结构的变化及其与水环境之间关系，对了解水生生态系统的变化、生态过程、水质状况等有着重要意义。为了解贵州草海高原湿地浮游动物群落特征、长期变化以及水质现状，笔者于2014年夏季（8月）和秋季（11月）对草海浮游动物和主要水质指标进行了两次调查采样，分析了浮游动物种类、多样性、空间分布及其水质评价，并通过和以往同季的研究数据进行对比，探讨了30年来草海浮游动物的变化状况。结果表明，草海浮游动物种类丰富，研究共检出浮游动物83属151种，其中原生动物31属60种，轮虫26属55种，桡足类15属18种，枝角类11属18种；优势种有5种，主要的优势种为桡足类的大型中镖水蚤（Sinodiaptomus sarsi）；草海浮游动物Shannon-Wiener多样性指数和Margalef丰富度指数较低，年均值分别为1.14和0.47。草海浮游动物群落结构季节变化明显，种类组成上，夏季110种，秋季75种，夏秋共有种有34种，季节更替率达77.5%；数量构成上，夏季丰度为1505.53 ind·L-1，秋季丰度506.66 ind·L-1，夏季明显高于秋季。利用综合营养状态指数和浮游动物群落参数对草海水质进行评价，结果显示2014年草海水质处于中营养-中污染水平。与历史时期相比，草海浮游动物种类变幅较小，但浮游动物丰度却大幅度降低了，优势种也发生了较大的改变，这可能与草海水质的剧烈变化有关，但具体的生态过程和驱动机制还需深入研究和长期监测。
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