[Background] Although the coal mine wastewater treatment by constructed wetland has succeeded remarkably, few studies can be found on the structure and function of microbial communities in constructed wetlands sediment. [Objective] The purpose of this study is to clarify the effect of constructed wetland on the coal mining wastewater treatment and the structure and function of microbial community. [Methods] The water quality at different sampling sites of constructed wetland in Zuoyun, Shanxi was monitored. Based on high throughput sequencing technology, V3?V4 region of the bacterial 16S rRNA gene in constructed wetlands sediment were sequenced. Then the composition of bacterial communities in sediment were analyzed. [Results] The quality of wastewater from coal mine was effectively improved after flowing through the constructed wetland. Removal efficiencies of biochemical oxygen demand (BOD5), chemical oxygen demand (CODCr), total nitrogen (TN) and total phosphorus (TP) in constructed wetlands were 76.2%, 93.4%, 73.4%, 99.3%, respectively. Illumina sequencing of 16S rRNA amplicons revealed that a total of 2 832 operational taxonomic units (OTUs) were detected. Sequence alignment results showed that a total of 51 bacterial phyla, 150 classes, and 753 genera were found. Among the 4 sampling sites, the dominant bacteria phyla were Proteobacteria (50.0%?64.7%) and Bacteroidetes (15.8%?21.2%). The sampling sites of M1, M2, and M3 had the highest abundance of β-Proteobacteria and γ-Proteobacteria, which were rich in ammonia nitrogen oxidation bacteria. The sampling site of M4 had the greatest number of bacterial OTUs with the highest diversity. There were significant positive correlations between the relative abundance of Azoarcus and contents of the TN, while significant negative correlations between the relative abundance of Sulfurimonas, Sulfuricurvum and the contents of NH4+-N. Moreover, the relative abundance of Novosphingobium was also positively correlated with the contents of the TP. [Conclusion] The effective treatment of coal mine wastewater is achieved after flowing through constructed wetland, and bacterial diversity plays a decisive role in the ecological function of constructed wetland.