Abstract: The problem of cyanobacteria bloom caused by eutrophication was a challenge to the protection of aquatic environment of Poyang Lake.In order to clarify the spatial and temporal distribution characteristics of cyanobacteria in Poyang Lake and the influencing factors, cyanobacteria were monitored in the eastern lake, main lake and inlet channel of Poyang Lake from 2019 to 2020.The redundancy analysis (RDA) was used for data analysis.Results showed that, a total of 128 species from 7 phyla were detected, including 15 species of cyanobacteria, accounting for 11.72% of the total number of species.The number of phytoplankton species and cyanobacteria species showed the distribution pattern of wet season > flat season > dry season, and the main lake > inlet channel > eastern lake.The number of cyanobacterial density ranged from 0 to 2.19×107cells/L in Poyang Lake, with the proportion of cyanobacteria at each site ranged from 0% to 83.98%.Among them, the densities of cyanobacteria showed a distribution pattern of the main lake > eastern lake> inlet channel , wet season > flat season > dry season, and 2020 >2019.Pseudanabaena sp.was the dominant cyanobacterial species in the eastern lake area, Microcystis sp.and Pseudanabaena sp.were the dominant cyanobacterial species in the main lake area and the inlet channel.Water temperature, suspended solids, permanganate index, wind speed and the particular lake current and wind field were the main factors affecting the distribution of cyanobacterial communities in the main lake.Transparency, suspended solids and permanganate index were the main factors affecting the distribution of cyanobacteria in the inlet channel.The distribution of cyanobacterial community in the eastern lake was the result of the combined influence of all factors.Phosphorus was no longer the limiting nutrient for cyanobacterial outbreak in Poyang Lake, which implied that reducing phosphorus pollution load was also an important means to prevent cyanobacterial bloom in Poyang Lake.