The temperature of the tool that converts electrical energy into heat energy is determined by its own power and the length of the power-on time. The wattage has a long power-on time, and the temperature rises quickly. On the contrary, the temperature is low, and the temperature of the wattage is low. Mica skeleton heating element and metal tube heating element, the electric iron made of mica skeleton heating element has simple structure, easy manufacture, relatively uniform heat generation and convenient maintenance. The disadvantage is that the heating wire is exposed to the air and oxidizes at high temperature. Short life, easy to be affected by humid air, poor insulation performance, electric iron made of metal tube electric heating element has good mechanical strength, long service life, high thermal efficiency, good moisture resistance, safety and reliability, but the manufacturing process is more complicated.