Underground tunnel excavation is still the main way of coal mining, some fracture stratum zones, non cemented soft strata and aquifer on coal seam roof must be encountered in the mining process. If there is misconduct in the excavation, a large amount of formation water may enter along the cracks and through mined-out subsidence areas into the tunnel to cause severe flooding accident, the excavation work will be severely affected, the well lane might be abandoned and even serious personal injury accident might happen. According to the disadvantages of traditional cement slurry, a kind of waterproof has been developed, which is mixed with water at ratio of 1∶1 with rapid condensation and high condensation strength and can be used at the temperature over 25℃. This cement slurry is tested in a mine water plugging operation, the well is 840m in height with outflow of 120m3/h, good water plugging effect is received.