Abstract: Enhancing microbial methane production from coal is an effective way to increase production of coalbed methane. In order to expand its strengthening means and explore the potential of kaolinite-enhanced anaerobic fermentation of coal gas production and its promoting mechanism, an anaerobic fermentation system was constructed with long-flame coal as the substrate. By testing and analyzing biomethane gas production, surface functional groups of residual coal before and after fermentation, intermediate key liquid phase products, microbial community structure and methanogenic metabolic pathway, the promoting effect of kaolinite on methane produced by anaerobic fermentation was investigated. The results show that adding kaolinite with a mass fraction of 0.5% to the coal-based anaerobic fermentation system can effectively strengthen the entire anaerobic fermentation process and improve the staged and cumulative methane production. The relative mass fraction of carbonyl carbon (C=O) and carboxyl carbon (COO−) on the surface of the residual coal decreased by 48.95% and 46.26%, respectively, after the addition of kaolinite, indicating that kaolinite effectively promoted the degradation of coal by microorganisms. From the early stage of anaerobic fermentation to the peak of gas production, the activities of hydrolytic bacteria and hydroacetic acid bacteria in the bacterial community in the kaolinite system were enhanced, which improved the hydrolysis efficiency of complex organic compounds in the early stage and provided more adequate substrates and nutrients for methanogenic bacteria. The gap between the layers of kaolinite can ease the accumulation of volatile fatty acids in the solution and provide a more stable and safe metabolic environment for methanogens. During the peak period of gas production, the pH value in the solution increases and Macellibacteroides is more active in the kaolinite group. The hydrogenotrophic methanogenic Methanobacterium gained more sufficient carbon dioxide and hydrogen as substrates, enhancing their activity. In the acetate-utilizing control group, the utilization efficiency of carbon dioxide and hydrogen was relatively low. However, after the addition of kaolinite, these substrates were more efficiently utilized by the methanogens, leading to a significant increase in methane production.