This paper is about the structure of phytoplankton communities in the autumn of 2010 in Anxing Wetland, Heilongjiang Province, China. The abundance of phytoplankton communities, cell density and dominant species were analyzed. In total, 146 taxa were identified from nine sampling sites. The 146 taxa included 6 divisions, 8 classes, 12 orders, 25 families, 45 genera, 128 species, 17 varieties and 1 form. Chlorophyta were dominant and accounted for 39.7% of the total phytoplankton, while Euglenophyta and Bacillariophyta accounted for 30.8% and 21.9%, respectively. The abundance of phytoplankton was 181.4×10⁶ cells/L. Dominance analysis showed that there were more than three dominant species at each sampling site, including Trachelomonas granulosa Playf., Cyclotella meneghiniana Kütz. and Trachelomonas granulosa var. crenulatocollis(Szab.) Hub. -Pest.. Cluster and non-metric Multi Dimensional Scaling analysis showed that nine sampling sites were divided into five groups and the composition of phytoplankton communities were significant different spatially when the similarity of the phytoplankton community reached to 60%. That was related to different ecological characteristics of each site. Canonical Correspondence Analysis showed that dominant specie change was mainly influenced by temperature and pH. In addition, a large number of β-mesosaprobic zone indicators and lower diversity index were monitored in Anxing Wetland, suggesting that the water quality from the wetlands might have been polluted.