The invention provides a preparation method of a high-
coercivity neodymium-iron-
boron magnet. According to the preparation method,
graphene is added to a
neodymium-iron-
boron powder, so as to effectively improve the strength of the
neodymium-iron-
boron magnet. Modifier Li<4-2x>M<3x>Ti<5-x>O<12>C is used to improve the
magnetic energy product of the neodymium-iron-boron
magnet, so as to perfect andimprove the performance of the neodymium-iron-boron magnet. A rare-earth
metal film is sputtered onto the surface of each
powder particle by using the magnetron
sputtering process; grain boundaries are diffused by means of pressing and
sintering;
rare earth metals enter the superficial
layers of neodymium, iron and boron to improve the anisotropies of the neodymium, iron and boron, with the neodymium, iron and boron hardly affected; and therefore, the purpose of greatly improving the
coercivity of the neodymium-iron-boron magnet can be achieved under the condition that remanent
magnetism hardly decreases. In addition, the neodymium-iron-boron magnet is pre-sintered by means of stepped heating, so that the temperature gradients at the exterior and center of the neodymium-iron-boron magnetdecrease; and when the
sintering temperature is reached, the temperature of the central part of a neodymium-iron-boron compact is allowed to reach the
sintering temperature rapidly, so as to improve the density and magnetic properties of the sintered neodymium-iron-boron compact.