NdFeB magnets (Nd-Fe-B) are composed of neodymium, iron, boron and a few transition metals, with high energy product and good coercive force. These magnets are extremely strong for their small size, metallic in appearance and found in simple shapes such as rings, blocks and discs. Neodymium magnets are developed rapidly and applied widely due to their perfect characteristic, rich raw material resource and reasonable price. But they are corrosive, easy oxidation and low working temperature. It makes them to be used in limited industries.