The effects of Nb addition on the crystallization behavior, microstructure, and magnetic properties of melt-spun Nd2Fe14B/alpha-Fe nanocomposite magnets have been studied. The addition of Nb can significantly improve the thermal stability of amorphous phase in as-spun alloys, narrow the range between the onset crystallization temperature and the optimal annealing temperature, restrain the initial formation and growth of alpha-Fe and Nd2Fe14B. A finer and more homogeneous microstructure can be obtained in the Nb-doped alloy than in the Nb-free alloy. And the Nb addition makes the grains more equiaxed shape. The Nd10Fe83Nb1B6 alloy annealed at 715 A degrees C for 10 min exhibits the improved magnetic properties, B (r) = 0.90 T, (i) H (c) = 750 kA/m, (BH)(max) = 120 kJ/m(3), the intrinsic coercivity and the maximum energy product increase by 25% and 14%, compared with the Nd10Fe84B6 alloy.