Under the condition of large mining depth, there are high ground stress and severe mining pressure activities brought about by the mining work. Under the coupling effect of high ground stress, strong mining pressure and ultra-high pressure water, with possible lower height of the back-mining working surface support, stuck and the roadway to be drastically deformed, and then water seeping out of the micro-fissure of the floor and the water output not large, but due to the rapid deterioration of the site environment, water and coal are mixed during the push mining process, which made the pump nest at the lowest point of the working surface to be silted up and the drainage equipment not run, which seriously affected the efficiency of the drainage system. The arrangement of the drainage system in complex situations such as the occurrence of small and medium-sized sudden water in the working surface of large mining depths was explored, so as to maximize the realization of "water-coal separation", thereby ensuring the efficient and reliable operation of the working surface drainage system.