Iron-based nanocrystalline alloy is an amorphous material formed by the rapid solidification process of an alloy composed of iron elements and a small amount of Nb, Cu, Si, and B elements. It can be obtained with a diameter of nanometer level, which is dispersed and distributed on an amorphous matrix, which is called microcrystalline and nanocrystalline materials. Nanocrystalline materials have excellent comprehensive magnetic properties: high saturation magnetic induction (1.2T), high initial permeability (8×104), low Hc (0.32A/M), low high frequency loss under high magnetic induction (P0 .5T/20kHz=30W/kg), the resistivity is 80μΩ/cm, which is higher than that of permalloy (50-60μΩ/cm). After longitudinal or transverse magnetic field treatment, high Br (0.9) or low Br value (1000Gs) can be obtained. ). It is the material with the best comprehensive performance on the market, and the best frequency range: 20kHz-50kHz. Widely used in high-power switching power supply, inverter power supply, magnetic amplifier, high-frequency transformer, high-frequency converter, high-frequency choke coil core, current transformer core, leakage protection switch, common mode inductor core. The magnetic permeability and Hc value of the nanocrystalline alloy are close to the crystalline high permalloy and cobalt-based amorphous, and the saturation magnetic induction Bs is comparable to that of the medium nickel permalloy. The heat treatment process is simple, and it is an ideal low-cost high-performance soft magnetic Materials; although the Bs value of nanocrystalline alloys is lower than that of iron-based amorphous and silicon steels, their high-frequency losses under high magnetic induction are much lower than those of them, and they have better corrosion resistance and magnetic stability. Compared with ferrite, nanocrystalline alloy has 2 to 3 times higher working magnetic induction on the basis of lower loss at lower than 50kHz, and the magnetic core volume can be more than doubled.