The structure of the electric heating tube includes a metal tube, a spiral heating wire, a crystalline magnesium oxide powder filling body, a lead-out terminal and a sealing assembly. In the center of the metal tube, a spiral iron chromium aluminum or nickel chromium alloy wire is provided as a heating element in the axial direction. Filling body. One end of the heating element heating wire is connected with the lead-out terminal of the heating tube, and the other end is directly welded with the metal tube body. The sealing assembly of the electric heating tube still uses the traditional screw connection. The electric heating tube of the electric heating tube superheated steam boiler is connected with the tube plate through a screw thread, and is directly inserted into the boiler body and the superheater cylinder which generate saturated steam. When the electric heating tube is used, three are in a group, and the three phases of A, B and c are respectively connected with the lead terminals of the three electric heating tubes. Since the other end of the heating wire in each electric heating tube is welded to the tube, the other ends of the three electric heating tubes are actually connected together to form a Y-shaped connection. The boiler shell has also become a neutral point, and it can work after being powered to heat water or saturated steam. Because the boiler shell becomes the neutral point, the boiler body using this type of heating element heating method must be well grounded, and calculation and installation should be performed according to the requirements of transformer grounding. The electric heating tube can be easily fixed on or removed from the boiler body by threads. Once the individual heating tube of the boiler is damaged, even if the boiler body is filled with water, as long as all the valves on the body are closed, the boiler water will not flow out when the tube is changed. It is very convenient to replace the electric heating tube.