Broadly speaking, all magnetic materials that can be magnetized by magnetic fields, in which the magnetic properties of the materials are mainly utilized, are used as magnetic materials. It includes hard magnetic material, soft magnetic material, semi-hard magnetic material, magnetostrictive material, magneto-optical material, magnetic foam material and magnetic refrigeration material, etc. The largest amount is hard magnetic material and soft magnetic material. The main difference between the hardmagnetic material and the soft magnetic material is that the hard magnetic material has high anisotropy field, high coercive force, large hysteresis loop area and large magnetic field required for the technology magnetization to saturation. Since the coercivity of the soft magnetic material is low and the magnetization of the technology is saturated and the external magnetic field is removed, it is easy to demagnetize, whereas the hard magnetic material remains long due to the high coercive force, magnetization to saturation and removal of the magnetic field Strong magnetic, so hard magnetic materials, also known as permanent magnetic materials or permanent magnetic materials. In ancient times, the use of natural ore magnetite polished into the required shape, used to guide or attract iron devices, the compass is one of the four major inventions in ancient China, the human civilization and social progress has made important contributions [2 ]. In modern times, the research and application of magnetic materials began after the industrial revolution, and in a short time to get rapid development.Nowadays, the research and application of magnetic materials in terms of breadth or depth are previously unparalleled, all kinds of high-performance The development and application of magnetic materials, especially rare earth permanent magnet materials, play an important role in promoting the development of modern industry and high-tech industry.