Nd-Fe-B permanent magnet is a tetragonal crystal system composed of Nd (neodymium), Fe (iron), and B (boron). It is the most practical and mass-produced permanent magnet material with the strongest magnetic properties, known as the "magnetic king". According to different preparation processes, Nd-Fe-B magnets can be divided into three categories: sintering, bonding, and hot pressing. Nd-Fe-B sintered magnets are anisotropic dense magnets manufactured using powder metallurgy methods; Nd-Fe-B bonded magnet is a non dense isotropic magnet made by bonding Nd-Fe-B microcrystalline powder and polymer. Nd-Fe-B hot pressed magnet is an anisotropic dense magnet made by hot pressing and deformation. Among them, Nd-Fe-B sintered magnets have the highest magnetic properties and the highest usage; Nd-Fe-B bonded magnets can be magnetized in any direction, and permanent magnets with complex shapes and high dimensional accuracy can be produced through molding and injection molding; The usage of Nd-Fe-B hot pressed magnets is the smallest, and currently only Datong Company in Japan is producing them in bulk. The main application area is in the EPS system of automobiles.