Based on the water plugging project of 2228 working face in Xingdong Mine, the plugging technology of water outlet channel under dynamic water condition was studied. Water inrush from floor was one of the main disasters threatening the safety production of coal mines in China. With the mining of lower coal group and the increase of mining depth, coal mines were threatened by Ordovician limestone confined water more and more seriously. After coal mining, under the joint action of mining stress and water pressure, floor rock mass would be destroyed and destabilized, and Ordovician limestone water inrush from floor fracture would be caused, which gradually became the main form of floor water inrush. After floor water inrush occurred, the primary problem was to block the outlet passage. At present, the blocking of outlet passage was limited to the still water condition, so it was necessary to carry out research on the sealing of outlet passage under the dynamic water condition.