The phytoplankton community in Hanfeng Lake Reservoir, located in the Three Gorges Reservoir Areas of Yangtze River, was investigated from Jun to August 2013. The results showed that 72 species belonging to 7 phyla of phytoplankton were detected in the water. The dominant species were Synedra, Navicula, Melosira, Cocconeis, Scenedesmus, Pseudoanabaena and Merismopedia. The phytoplankton at the entrance of Donghe River was mainly composed of Bacillariophyta, while that at the entrance of Nanhe River was dominated by Cyanophyta and Chlorophyta. Canonical correspondence analysis was applied to investigate the relationships between the distribution of phytoplankton and the environmental factors. The results showed that the species of phytoplankton at the entrance of the Donghe River were influenced by the physiochemical properties of the water, while those at the entrance of Nanhe River were affected by the nutrient status of the water. The key factors influencing the distributions of phytoplankton were temperature, dissolved oxygen ( DO) , pH, total nitrogen ( TN) , dissolved nitrogen ( DN) and dissolved phosphorus ( DP) .