The microstructure of the α-Fe/Nd 2 Fe 14 B nanocomposite magnets prepared by electropulsing heating amorphous Nd 8 Fe 84 Co 3 B 5 has been studied by employing X-ray diffraction (XRD) and transmission electronic microscopy (TEM). The grain size d of the α-Fe phase keeps almost invariable, e.g., d≈18–19 nm, with the increase of its volume fraction during the electropulsing heating process, indicating that the crystallization process of the α-Fe phase dominantly depends on the enhancement of nucleation rate. The grain sizes of both the α-Fe and the Nd 2 Fe 14 B phases, d α-Fe =19 nm and d NdFeB =27 nm, are smaller as compared to those in the nanocomposites prepared by annealing Nd 8 Fe 84 Co 3 B 5 in a normal furnace, d α-Fe =23 nm and d NdFeB =39 nm. This leads to an enhanced maximum energy product (BH) max =128 kJ/m 3 in the nanocomposite magnets.