In order to investigate the role of bacterial microbial communities in the pathogenesis of poplar wet heartwood, the wet heartwood and normal wood of 6-year-old Populus deltoides Bartr. ‘Huashi2’ were studied, and high-throughput sequencing of the V5-V7 region of the 16S rRNA gene was used to sequence and analyze the bacteria informatically. Principal component analysis, α-diversity index analysis and microbial network analysis techniques were used to explore the differences in the structure and composition of the bacterial microbial communities in the wet heartwood and normal timber of 6-year-old poplar. The results showed that:At the genus level of the bacterial microbial community of 6-year-old Populus deltoides Bartr. ‘Huashi2’ wet heartwood and normal timber, the highest bacterial abundance was found in the genera of Ralstonia and Bacteroides, and the genera of Bacteroides , Pleomorphomonas and Hydrogenispora accounted for a significantly higher proportion of the wet heartwood than that of the normal timber ( p<0.05). Functional analysis of microbial communities showed that Ralstonia were mostly phytopathogenic bacteria, which widely existed in wet heartwood. Analysis of the alpha diversity index showed that wet heartwood community diversity and species distribution evenness were higher than that of normal wood, and the total number of species was lower than that of normal wood.. Co-occurrence network study showed that there were more competition and antagonism among bacterial microorganisms in poplar normal timber, and the community was more unstable, while the bacterial microbial community in wet heartwood was more stable. The analysis of key microorganisms showed that the key bacterial microorganisms in the wet heartwood of 6-year-old poplar were Aquabacterium, WCHB1-32, etc., and the key bacterial microorganisms in the normal heartwood of 6-year-old poplar were Pleomorphomonas, Dysgonomonas, etc. These key microorganisms play an important role in stabilizing the microbial network structure of wet heartwood. In this study, we found that poplar wet heartwood formation is influenced by multiple factors and results from the joint action of microbial communities.