Nanocomposites alphaFe/Fe3B/Y2O3 and epsilon-Fe3N/Y2O3 were prepared by a melt-spun technique, and the subsequent hydrogenation, oxidation and nitrogenation treatments, respectively. The effective electromagnetic wave absorption (RL<-20 dB) was obtained in a frequency range of 2.7-6.5 GHz on resin composites of 80 wt% alpha-Fe/Fe3B/Y2O3 powders, with thickness of 6-3 mm; the epsilon-Fe3N/Y2O3 resin composites exhibited good microwave absorption properties in the 0.6-4.4 GHz range.