Abstract: There are obvious differences between underground coal mine and surface environment. The studies of the distribution and diversity of microbial community in the underground coal mines are important for exploring the water rockgasbiological mechanism. In this study, eight coal deposit samples were collected from the level of -700 m in Quantai Coal Mine, Xuzhou, East China. The physical and chemical indices of the samples were tested and Miseq highthroughput sequencing was performed. A total of 35 bacteria phyla were detected in the eight samples, with Proteobacteria, Firmicutes, and Actinobacteria together accounting for more than 80% of the total abundance. Proteobacteria and Firmicutes were mainly distributed in rock lanes, while Actinobacteria were mainly distributed in coal lanes. The dominant bacterial genera of coal mines included Lactococcus, Pseudomonas, Mycobacterium, and Bacillus. In general, the abundance and diversity of bacterial communities in rock lanes were higher than those in coal lanes. pH was the key factor affecting the abundance of bacterial community in coal mine (R²=0.766,P<0.05) at the phylum level. pH was positively correlated with Actinobacteria, Firmicutes and Latescibacteria, while negatively correlated with other phyla. The concentrations of total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP) and sulfate also affected the community abundance distribution. Therefore, the influence of underground microorganisms should be fully considered when examining coal mine pollution mechanism and pollutant migration.

Key words: underground coal mine, high-throughput sequencing, bacterial community, bacterial diversity, environmental factor.