The present invention discloses a rare earth permanent magnet and a method for preparing same. The material of the rare earth permanent magnet has a heavy rare earth element volume diffusion phenomenon at a depth of 5 μm to 100 μm from the surface of the magnet to the interior of the magnet along the magnetic field orientation direction, thereby forming a volume diffusion layer region; the volume diffusion layer region is divided into magnet units having a volume of 10*100*5 μm, and the concentration difference of the heavy rare earth elements of the magnet units at different positions in the volume diffusion layer is below 0.5 at %. The present invention provides a sintered NdFeB magnet of high intrinsic coercive force Hcj on the premise of not influencing the remanence Br and the maximum magnetic energy product (BH)max of products. In the method for preparing the rare earth permanent magnet, microwave heat treatment is performed on a blank magnet coated with heavy rare earth source slurry in a vacuum condition. This method can effectively improve the heating efficiency, reduce the heat treatment time, lower the energy consumption, and reduce the production cost of the magnet.