The utility model provides a RH vacuum refining explosion -proof equipment, the device include: hemisphere lid (8), support frame (7), a plurality of cylinder, cylinder switching -over valve (96), magenetic exchange valve (85) and trachea (83), hemisphere lid (8) be hollow hemispheroid structure, the one end and magenetic exchange valve (85) the intercommunication of trachea (83), the convex surface that hemisphere lid (8) was followed to its other end penetrates to the concave surface, pipeline and cylinder intercommunication are passed through to the one end of cylinder switching -over valve (96), and its other end drives actuating cylinder's piston rod extension through the compressed air who puts through, utilize above -mentioned device, the hemisphere that piston rod through the cylinder promoted hollow hemispheroid is covered closely and is leaned on to hot return bend connector to adopt the mode of carrying inert gas such as filling nitrogen gas to get into hot return bend, dispel isolated preheating oxygen, the coal gas of burning, take place the detonation accident in preventing hot return bend, improve the safety and stability nature that vacuum refining smelts production.