A mult-layer-structure rare-earth permanent magnet and a preparation method thereof, a rare-earth permanent magnet being comprised of a three-layer structure of primary-phase crystal grains and rare-earth-rich phase, the primary-phase crystal grains being separated, in accordance with different chemical compositions, into a three-layer structure comprising a core layer, a middle layer and a shell layer, the component compositions thereof respectively corresponding to: R1-T-B, R2-T-B and R3-T-B, wherein, R1 comprising at least one of Ce and La, R2 comprising at least one of Pr and Nd, R3 comprising at least one of Dy, Tb and Ho, T comprising at least one of Fe and Co, and B comprising a boron element. The rare-earth-rich phase comprising one or a plurality of the rare-earth elements Ce, La, Pr, Nd, Dy, Tb, Ho and Gd. A method for preparing a rare-earth permanent magnet comprising: using a double-alloy process to prepare a magnet blank, then using a grain boundary diffusion process to make a multi-layer-structure rare-earth permanent magnet.
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