The invention discloses a sintered neodymium-iron-boron magnet without heavy rare earth and a preparation method of the sintered neodymium-iron-boron magnet. The constituent of sintered neodymium-iron-boron magnet is Re<Alpha>Fe<100-Alpha-Beta-Gamma>B<Beta>M<Gamma>, wherein Re is a light rare earth element and comprises an element selected from one or more than one of La, Ce, Pr, Nd, Sm and Eu; M is an addition element and comprises an element selected from one or more than one of Ti, V, Cr, Ni, Zn, Ga, Ge, Al, Zr, Nb, Co, Cu, Ag, Sn, W, Mo, Pb, Bi, Mg and Pd; Fe comprises Fe and an inevitable impurity; Alpha, Beta and Gamma are respectively atomic percentage of each element; and Alpha is more than or equal to 12 and less than or equal to 17, Beta is more than 5 and less than or equal to 6.5, and Gamma is more than or equal to 0.1 and less than or equal to 5. The sintered neodymium-iron-boron magnet has the advantages that low-melted light rare earth micro-powder is used for achieving a grain refinement effect on liquid-state coated nano metal powder moved and uniformly distributed in a grain boundary during high-temperature sintering, and moreover, the light rare earth micro-powder can simultaneously play in improving magnetic performance of a product.