Abstract: In order to clarify the composition of bacterioplankton communities and the environmental factors involved, we collected samples of bacterioplankton and monitored some main environmental indexes in February 2018 and July 2018 respectively in the Daye Lake. Basing on 16S rRNA high-throughput sequencing, we analyzed and compared the differences in composition and diversity of bacterial communities in the Daye Lake during the dry season and the wet season. We conducted the redundancy analysis (RDA) to explore the relationship between environment factors and composition and diversity of bacterial communities in the water. The results showed that the bacterioplankton had high microbial diversity in the Daye Lake. The Shannon indexes of dry season and wet season were 3.856±0.642 and 4.165±0.608, respectively. The main bacterial categories were Proteobacteria, Actinobacteria, Cyanobacteria, Bacteroidetes, Firmicutes, Planctomycetes, Verrucomicrobia, Chlorobi and Chloroflexi. In this case, the dominant bacteria was Betaproteobacteria (44.73%) in dry season. In wet season, however, the dominant bacteria were Cyanobacteria (31.39%) and Actinobacteria (31.37%). Redundancy analysis showed that nitrate (NO^-₃-N), temperature (T) and total nitrogen (TN) were the main environmental factors affecting the distribution of bacterial communities.