The invention relates to an explosion-proof device long in service life. The explosion-proof device comprises a pipeline at the corner. 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 theexplosion-proof opening; elastic devices are arranged on the two sides of the explosion-proof opening correspondingly; the lower ends of the two elastic devices are both fixedly connected with the pipeline, and the upper ends of the elastic devices are fixedly connected with the explosion-proof cover; a circle of sealing ring is arranged at the edge of the upper end of the explosion-proof opening, and a first magnetic ring is arranged at the circle outside the sealing ring; a second magnetic ring is arranged on the explosion-proof cover and located on the corresponding upper portion of the first magnetic ring; and a plurality of limiting rods are arranged in the portions, corresponding to the explosion-proof cover, of the pipeline, are in an annular shape to embrace the periphery of the explosion-proof cover and are all fixedly connected with the pipeline. Compared with the prior art, the explosion-proof device is simple in structure and stable in operation, a smelting furnace can beclosed automatically, airtightness is good, the situation that the elastic devices are twisted due to deviation is avoided, and the service life is long.