Abstract: Using CANOCO45 software, we investigated the difference of the structure of phytoplankton communities in Xianghai and Chagan Lake wetlands,  combined with the difference of water environmental chemical factors in wetland water supplement, and analyzed the causes of the difference of phytoplan
kton community structure. The results show that the geographical and climatic conditions are similar to those of Xianghai and Chagan Lake wetlands, there are pollution phenomena of the water environmental chemical factors in Xianghai and Chagan Lake wetlands, and the pollution degree of water environment in the Chagan Lake wetland is more serious than that in Xianghai wetland. Furthermore, the structure of phytoplankton communities is similar in the two wetlands, and the abundance of Cyanophyta is the largest, the species and dominant species of phytoplankton in Chagan Lake wetland are less than those in Xianghai wetland, and the number of detected species in each phylum exist certain differences.  pH, total phosphorus (TP), biochemical oxygen demand (BOD5) and bicarbonate are the main water environmental chemical factors affecting the distribution of phytoplankton in the Xianghai wetland, while pH, TP, total nitrogen (TN), dissolved oxygen(DO) and BOD5 are the main water environmental chemical factors affecting the distribution of phytoplankton in the Chagan Lake wetland. The significant differences of characteristics of water environment and structure characteristics of phytoplankton community between Xianghai wetland and Chagan Lake wetland are mainly caused by land use degree and the characteristics of supplementary water.

Key words: Xianghai wetland, redundancy analysis, water environmental chemical factor, Chagan Lake wetland, phytoplankton community