In order to explore the seasonal variation and influencing factors of bacterial community structure in storage reservoirs, the impact of environmental factors must first be examined. In this study, the seasonal variation in bacterial community structure and its response to water quality factors were explored by monitoring the water quality of Qingdao Jihongtan Reservoir, the only reservoir of the Yellow River diversion project, using high-throughput sequencing technology and symbiotic network analysis. The results showed that the diversity and richness of bacterial communities were highest in summer and lowest in winter, and those in the inlet were higher than those in the outlet. The structure of the bacterial community was similar in spring and winter and in summer to autumn. The dominant bacteria phyla were:Actinobacteriota (6.63%-57.38%), Proteobacteria (11.32%-48.60%), Bacteroidota (5.05%-25.74%), and Cyanobacteria (0.65%-24.74%). Additionally, the abundances of Chloroflexi, Dependentiae, Fusobacteriota, and Margulisbacteria were the highest in autumn and the lowest in winter. The dominant bacterial genera were:hgcI_clade (3.72%-34.66%), CL500_29_marine_group (0.31%-20.13%), and Limnohabitans (0.16%-10.37%). Further, the abundances of Flavobacterium, Polaromonas, and Rhodoferax were the highest in winter and the lowest in summer; the trend of Domibacillus and Limnobacter was the opposite. The abundance of Proteobacteria and Campilobacteria in the inlet was significantly higher than that in the outlet, and the Planctomycetota showed the opposite. The abundances of Dinghuibacter, Arenimonas, and Rhodobacter in the inlet were significantly higher than those in the outlet. Competition and antagonism dominated the interaction relationship of bacterial communities in spring, whereas mutualism dominated in winter. There were significant differences among key species in the symbiotic network at different seasons and sampling sites. Water temperature, DO, water storage capacity, and water storage sources had a great influence on bacterial community structure in the Jihongtan Reservoir.