Water accumulation in the mining area is a major water hazard that affects the safety production of coal mines. Whether the amount of water in the mining area can be accurately estimated and the water in the mining area can be purposely and systematically released is the key to control the flooding. Taking 51020 roadway in 410 area of Meiyukou Mine as the object of study, the amount of water accumulation in the mining area was accurately calculated by measuring the water pressure of water exploration and release holes, calculating the water level, comprehensively analyzing the hydraulic connection, back-calculating the water filling coefficient, circling the water accumulation range and determining the water accumulation elevation in the drainage process, which provided a reliable technical basis for water exploration and release work.