Abstract: A novel electron beam irradiation method and a novel powder mixture method were employed to modify the surface of a carbon steel substrate.By optimizing the electron beam parameters, chromium carbide is in-situ synthesized in the surface composite layer.The surface composite layer was analyzed with optical microscope, SEM, EDAX and XRD analysis.There are two main phases in the surface composite layer, one is chromium carbide M₇C₃(M=Fe, Cr)and Cr₇C₃, the other is austenite.The primary chromium carbide shows a typical hexagonal shape, while the eutectic chromium carbide finely diffuses in the austenite structure.The microhardness of the composite layers was 2.7 times higher than that of the steel substrate, which provides a notable improvement on the wear resistant property of the surface layer.