Abstract: In order to examine the phytoplankton situation of Hanfeng Lake in the Three Gorges Reservoir Area and evaluate the water body situation in the lake area during the dry season, the phytoplankton community in Hanfeng Lake was investigated and analyzed in October 2022. The results showed that 61 species of phytoplankton found belong to 43 genera, 26 families, 6phyla, including 13 species of diatoma, 8 species of cyanophyta, 32 species of chlorophyta, 4 species of cryptophyta, 2 species of gymnophyta and 2 species of dinoflagellate. In species number, Chlorophyta was dominant; The highest biomass of phytoplankton in Nanhe River and Donghe River entering the lake wwere 8.2 mg/L and 7.17 mg/L respectively, which was in the middle of the lake and the lowest in the outlet; The lake has the highest Wiener index and the most abundant species, indicating that its biodiversity was the highest, and all kinds of phytoplankton had significantly increased. The lake outlet was 2.23 and the number of species was the lowest among the five survey sites, indicating that its biodiversity was low, and cyanobacteria in the water body rapidly proliferated and formed an absolute advantage; The sampling points of phytoplankton species could be divided into one group at the lake inlet and one group at the lake inlet and outlet, which may be related to the close geographical and spatial location of the sampling points.According to the water quality status table represented by phytoplankton diversity index, the overall water quality of Hanfeng Lake in the dry season in October was in good condition during the survey.