The invention discloses a sintered neodymium-iron-boron magnet and a preparing method thereof. The sintered neodymium-iron-boron magnet is prepared in the mode that Ce-enrichment main-phase alloy powder and low-melting-point TeHy auxiliary-phase powder are evenly mixed, sintered and subjected to three-section tempering. The mass-percent chemical formula of the Ce-enrichment main-phase alloy powder is (CexRe1-x)aFe100-a-b-cTMbBc. Re is one or more kinds of Pr and Nd, TM is one or more kinds of Co, Al, Cu, Ga, Nb and Zr, x ranges from 0.2 to 0.5, a ranges from 30 to 32.5, b ranges from 0.3 to 2.5, c ranges from 0.9 to 1.2, and Te is one or more kinds of La, Ce, Pr and Nd. The sintered neodymium-iron-boron magnet and the preparing method have the advantages that the performance reducing range caused by adding Ce is reduced, the utility ratio of Ce resources is increased, the preparing cost of sintered neodymium iron boron is saved, the Ce stacking problem is solved, the healthy-stable development of the rare earth industry is promoted, and important actual significance is achieved.