A magnetic core refers to a sintered magnetic metal oxide composed of various iron oxide mixtures. The magnetic core means that in order to increase the magnetic induction intensity of the electromagnet, a magnetic conductive substance body is arranged in the magnetic circuit of the inductance coil. Core in the use of soft magnetic materials to electromagnetic induction principle of high-frequency electronic transformer is the most critical component. The main development direction of the magnetic core material is to reduce the loss, widen the temperature range of use and reduce the cost. The main development direction of the core structure is how to form a planar core, a chip core and a thin film core with the best shape and size (parameters of electromagnetic performance, heat dissipation, usage and cost). Now a variety of soft magnetic materials, are constantly improving and developing to compete for high-frequency electronic transformer market.