The mold electric heater uniformly distributes the high-temperature resistance wire in the high-temperature resistant stainless steel seamless tube, and densely fills the crystalline magnesium oxide powder with good thermal conductivity and insulation performance in the void portion. This structure is advanced not only advanced, but also has high thermal efficiency and uniform heat generation. When a current flows through the high-temperature resistance wire, the generated heat is diffused to the surface of the metal tube by the crystalline magnesium oxide powder, and then transferred to the heated member or the air gas to achieve the purpose of heating.