Rare earth permanent magnet materials. The main rare earth cobalt permanent magnet material and NdFeB. The former is an intermetallic compound of a rare earth element cerium, praseodymium, lanthanum, neodymium and cobalt formed up to 150 times the energy product of carbon steel, 3 to 5 times the aluminum-nickel-cobalt permanent magnet materials, ferrite permanent magnet 8 ~ 10 times, low temperature coefficient, magnetic stability, the coercive force of up to 800 kA / m. Mainly for low-speed torque motor, start the motor, sensor, magnetic thrust bearing magnetic system. NdFeB is the third generation of rare earth permanent magnet materials, its remanence, coercivity and the maximum energy product higher than the former, non-friable, have good mechanical properties, low alloy density, magnetic components in favor of light , thin, small and ultra-miniaturization. But its magnetic temperature coefficient is high, limiting its application.