The electrothermal heating tube used in laying machines is more widely applied in various household appliances and industrial electric heating equipment than electric heating wire. Its structure involves placing a spiral wire that has been coiled and shaped into a metal tube, with magnesium oxide powder, which has good thermal conductivity and insulation properties, tightly filled in the gap between the spiral wire and the tube. The tube is then sealed with a heat-resistant adhesive for insulation. This metallic electric heating element can heat air, metal molds, and various liquids (water, oil, corrosive acidic or alkaline liquids). The electric heating tube is characterized by its simple structure, high mechanical strength, ability to be bent into various shapes, long lifespan, energy-saving properties, easy installation, non-polluting nature, and high thermal efficiency.