The utility model discloses a B-type constant-pressure explosion valve device for a slurry injection bag hole sealing device for a gas discharging hole of a coal mine. The B-type constant-pressure explosion valve device comprises a slurry injection pipe, explosion holes are formed in the wall of the slurry injection pipe, the slurry injection pipe is sleeved with an explosion pipe wrapping the explosion holes, and locking hoops are tightly pressed on the outsides of the two ends of the explosion pipe in a sealed mode. The B-type constant-pressure explosion valve device is compact in structure, easy and convenient to machine, low in material cost, high in performance cost ratio and capable of being used in cooperation with the slurry injection bag hole sealing device for the gas discharging hole of the coal mine. In a slurry injection process, when slurry injection pressure reaches a certain value, timely response can be achieved, the explosion pipe explodes, the flow direction of cement slurry is changed, bags are filled in good condition, a hole between the two bags is blocked through slurry injection, the purpose of gas blocking is achieved, and the B-type constant-pressure explosion valve device is suitable for a slurry injection environment of the gas discharging hole of the underground coal mine.