Abstract: Coal seams occur in Peat formation formed by sediments, often used as aquiclude or aquitard in coal production. However, in Barapukuria coal mine in Bangladesh, No.VI coal seam is rich in water, shows a typical hydrogeological phenomenon that the coal seam becomes an aquifer, which is rare in coal mining process both in China and abroad. From the formation mechanism of coal and the microstructure and tectonic development characteristics of coal, the structure of rich in water of coal was revealed. Based on MTS815 rock mechanics test system, the permeability of No.VI coal was tested, and the internal structure of coal seam was revealed. Through the permeability analysis of roof and floor, combined with hydrogeological tests, the hydrogeological concept model of thick coal seam water storage structure was analyzed. Hydraulic connectivity test was applied to identify the main source of water supply in thick coal seam. The formation mechanism of thick coal seam as an aquifer was revealed by the three key factors, which are the structure of the coal body, the water storage structure and the recharge water source. The study shows, coalification of organic matter and the formation stress make a effective pores and water cracks development in coal body, in case of better supply conditions and meeting the geological structure of the aquifer, the coal seam can form an aquifer. Aiming at the characteristics of coal seam water, put forward the technical system for groundwater prevention and control in thick coal seam, which provides technical support for the area of coal seam as the aquifer.