Abstract:Investigations on the phytoplankton were carried out at 10 stations in Anbanghe wetland, a type of cold regions swamp, in summer 2005 and spring 2006. Phytoplankton community classification was undertaken by multivariate analyses, such as cluster analysis and metric multidimensional scaling analysis (MDS).92 common species occurred in both seasons, and 37 taxa and 82 taxa were identified in spring and summer, respectively. In spring the average abundance was 95.26×104ind./L, and in summer was 268.45×104ind./L. Based on the calculation of Bray-Cartis similarity matrix according to species abundance compositions of each station, cluster and MDS analysis showed that three communities can be distinguished in both seasons:(i) the central community, in spring, was Tabellaria flocculosa-Pediastrum tetras community, and in summer was P. tetras community, (ii) the margin community, in spring, was Cyclotella meneghiniana-Synedra acus community, and in summer was Anabaena sp.-Microcystis aeruginosa-C. meneghiniana community, (iii) the lotus flower pond community and Raphidiopsis mediterranea community in spring, and Merismopedia glauce community in summer. Phytoplankton composition, abundance, and diversity of each community were different between spring and summer, and positively correlated to the change of environmental factors between seasons.