The utility model discloses a sealing structure of a heating tube. Wherein the insulating part is used for fixedly supporting a conductive terminal, and the sealing part is used for being connected with a heating tube body. The insulator is mounted at the top of the flange plate; the sealing piece is tightly connected with the insulating piece and mounted at the bottom of the flange plate; the insulating part is provided with a drainage hole, the sealing part is provided with a first through hole, gas in the heating pipe body can penetrate through the sealing structure of the heating pipe through the drainage hole and the first through hole to be exhausted after being heated, and when the heating pipe body is broken, heated fluid can penetrate through the sealing structure of the heating pipe through the drainage hole and the first through hole to be exhausted. By means of the design, in the heating process of the heating pipe, gas in the pipe can be exhausted out of the heating pipe through the first through hole and the drainage hole when heated to expand, and when the heating pipe is not heated and contracts back to the original shape, the gas enters the pipe body again; and when the heating pipe body is accidentally broken, the heated fluid can be discharged through the first through hole and the drainage hole and cannot be sprayed out to scald workers, so that the safety is higher.