The invention relates to a warning explosion-proof device comprising a pipeline at the corner. One end of the pipeline communicates with a furnace chamber channel. The other end of the pipeline communicates with a flue gas discharge channel. The pipeline is provided with an explosion-proof opening. An explosion-proof cover is arranged at the upper end of the explosion-proof opening. The two sidesof the explosion-proof opening are both provided with elastic devices. The lower ends of the two elastic devices are both fixedly connected with the pipeline. The upper end of each elastic device is fixedly connected with the explosion-proof cover. A seal ring is arranged on the edge of the upper end of the explosion-proof opening. A first magnetic ring is arranged outside the seal ring. A secondmagnetic ring is arranged on the explosion-proof cover. The second magnetic ring is correspondingly located above the first explosion-proof ring. The pipeline is provided with a warning device. The explosion-proof cover is provided with a pressure relay. The warning device is connected with a power source through the pressure relay. Compared with the prior art, the warning explosion-proof device is simple in structure, stable in operation, capable of automatically closing a smelting furnace and good in seal performance and reminds operation personnel to conduct treatment.