Abstract: The effects of Nb additions on the magnetic properties, phase composition, exchange coupling and initial magnetization curve of (Nd_0.5Ce_0.5)₁₃Fe_82-xNb_xB₅melt-spun alloys were investigated in this paper.It is found that the addition of Nb can inhibit the forming of α-Fe and improve significantly the magnetic properties of the alloys.The optimum magnetic properties has been obtained with 0.5 %Nb additions.ThecoercivityH_cj and maximum energy product (BH)_max increased with increasing Nb content from 0 to 0.5 %.The coercivity increased from 777 kA/m for Nb-free sampleto 900 kA/m for 0.5 % Nb additions sample, and the maximum energy product also varied from 64 kJ/m³ for x=0 to 78 kJ/m³ for x=0.5, while the remanence of alloys decreased from 0.71 to 0.70T, only a slight difference from the Nb-free alloy.The exchange coupling between the grains in the alloy with the addition of Nb has also been enhanced.The obvious difference among the initial magnetization mechanism of the alloy has appeared.