Abstract: To evaluate the plankton characteristics of the Poyang Lake National Nature Reserve after the drought occurred in spring 2011, the community structure and spatial distribution of plankton in the Poyang Lake National Nature Reserve were investigated and analyzed in August, 2011. A total of 97 phytoplankton and 42 zooplankton species were identified, which belonged to 49 and 23 genera, respectively. The zooplankton were consisted of 13 species of protozoa, 23 species of rotifera, 3 species of cladocera and 3 species of copepoda. The numbers of plankton species in Lake Dahuchi and Zhushihu were more than that of the other lakes and rivers. The abundances of plankton among each lake and river were significantly different, and varied from 260 to 8.18106 cells/L for phytoplankton and 3630 to 73173 ind./L for zooplankton, respectively. The results showed that the abundances of plankton in Xiu River and the lakes that located at the west of Gan River, were significantly higher than that of Gan River and the other lakes. Statistical analysis indicated that the dominant species of phytoplankton in the Poyang Lake National Nature Reserve were Anabaena flos-aquae, Scenedesmus quadricauda, S. bijuga, Melosira granulata var. angustissima, M. granulate, M. graunlata var. angustissima f. spiralis, Synedra acus and Fragilaria capucina, while the dominant species of zooplankton were Stentor amethysinus, Difflugia lobostoma, Centropyxis discoides, Strombidim viride, Brachionus diversicornis, B. bennini, Trichocerca rousseleleti, T. longiseta and Asplanchna girodide. The maximum values of diversity indices (H') and evenness (J) of both phytoplankton and zooplankton were 2.41 and 0.96, respectively. The values of abundance (Dm) of plankton were both less than 3. Evaluated with the diversity indices (H'), evenness (J) and abundance (Dm) of plankton, the water qualities of lakes and rivers in the Poyang Lake National Nature Reserve were -type of pollution, except Lake Banghu and Meixihu.