Nickel-chromium wire is used as the heating material, mica soft board is used as the insulating material, and thin metal plate is outsourced. Common metal plates are copper, stainless steel, stainless steel, aluminum, etc. The mica heating coil has high-insulation refractory mica wound around the heating wire. The heating wire core has a good insulating refractory layer at both ends, and is first made into a flat plate and then mechanically twisted. Since the mica heating ring is made of mica as a raw material, it can be used for small size heating of the nozzle and heating on the barrel of the plastic machine. The mica heating ring has the characteristics of reasonable structure, beautiful appearance, stable performance, uniform heating, fast heat dissipation, long service life, good insulation performance and high pressure resistance.