The diameter of the heating wire is the parameter related to the highest operating temperature. The larger the diameter of the heating wire, the easier it is to overcome the deformation problem at high temperature and prolong its service life. The heating wire shall be operated below the maximum service temperature and shall have a diameter of not less than 3 mm and a thickness of not less than 2 mm. The service life of the heating wire is also largely related to the diameter and thickness of the heating wire. When the heating wire is used in a high temperature environment, a protective oxide film is formed on the surface, and the oxide film will age after a certain period of time, forming a cyclic process of continuous generation and destruction, and this process is a process of continuously consuming internal elements of the electric furnace wire. The electric furnace wire with larger diameter and thickness has more elements and a longer service life.