As we all know, the higher the magnetic permeability of the current transformer core, the smaller the measurement error and the higher the measurement accuracy. The silicon steel current transformer core cannot obtain sufficient measurement accuracy in the case of low ampere-turn with small turns ratio. Iron-nickel permalloy cores have low magnetization and high cost, so their applications are limited. Nanocrystalline magnetic cores are more and more widely used in power supply systems, power measurement and control systems and other fields because of their high magnetic permeability, high magnetization and low cost, and are used in precision precious current transformers.