The wear behavior of nanostructured hypoeutectic Fe_94.3B_5.7 alloy was investigated in comparison with coarse grained counterpart. The friction coefficient of the Fe_94.3B_5.7 alloy changed slightly with grain size. While the wear rate decreased as the grain size decreased to nano scale. Both Fe₂O₃ and Fe₂SiO₄ oxides were found on the worn surfaces in the nanostructured Fe_94.3B_5.7 alloy, but only a few oxide films were observed for the coarse grained counterpart. These results suggested that the nanostructured eutectic was conducive to forming oxide films on the worn surface of the Fe_94.3B_5.7 alloy, and improved the wear resistance.