Effect of pulsed high-energy electron beam on the surface modification and the state of surface layer and wear resistance of AZ91 magnesium alloy have been investigated in this study. Optical microscope (OM) and X-ray diffraction (XRD) were employed to characterize the microstructure and phase composition of the modified surface layer. It was found that the thickness of melted layer on the surface varied with electron beam current and the numbers of pulses, the treated surface layer exhibited higher hardness than AZ91 alloy. The friction coefficient and the wear volume of AZ91 alloy after electron beam treatment decrease markedly. The wear resistance of treated samples were significantly improved, which may be attributed to high hardness as a result of grain refinement.