The original working face length design of No. 9 coal seam in north shaft of Dongpang Mine was 70 m. Due to the relatively short working face length, the mine with a series of problems such as high coal mining rate, tight mining succession and large loss of coal pillars, the systematic research of the project increased the actual working face length of the high-risk area of hydrogeological conditions to about 90 m, providing theoretical guidance for increasing the length of the pressurized mining face in the high-risk area, and also for the efficient and safe production and water control technology of lower coal seam mining.