The invention relates to an explosion-proof device of a smelting furnace. The explosion-proof device comprises a corner pipeline; one end of the pipeline communicates with a furnace chamber channel, and the other end of the pipeline communicates with a smoke discharging channel; an explosion-proof opening is formed in the pipeline; an explosion-proof cover is arranged at the upper end of the explosion-proof opening; elastic devices are arranged on the two sides of the explosion-proof opening; the lower ends of the two elastic devices are fixedly connected to the pipeline, and the upper ends ofthe elastic devices are fixedly connected to the explosion-proof cover; a sealing ring is arranged at the edge of the upper end of the explosion-proof opening; a first magnetic ring is arranged on the outer circle of the sealing ring; a second magnetic ring is arranged on the explosion-proof cover and is located above the position, corresponding to the first magnetic ring, of the first magnetic ring; the position, close to the explosion-proof opening, of the pipeline is sleeved with a refrigerating ring; a temperature relay is arranged on the pipeline; and the refrigerating ring is connectedto a power source through the temperature relay. Compared with the prior art, the explosion-proof device has the advantages of being simple in structure, stable in operation, capable of automaticallyclosing the smelting furnace, good in sealing performance and capable of lowering the explosion probability of the explosion-proof cover.