In this study, 45# carbon steels were boronized, borosulphurized and RE-borosulphurized at 950 degrees C for 6 h, respectively. The samples were then characterized by scanning electron microscopy, X-ray diffraction, Auger electron spectroscopy, microhardness tester and ring-on-block wear tester. It has shown that the diffusion front (the interface between the diffusion layer and the substrate) of the boride layer (BL) and the boro-sulfide layer (BSL) is saw tooth shape, while the diffusion front of the RE-boro-sulfide layer (RBSL) is flat. Compared with BSL layer, RBSL layer has a smaller and more uniform grain size, and a flatter hardness gradient from the surface to the diffusion front. The RBSL layer, consisting of an outer layer (from surface to 30 mu m) mainly composed of Fe-B and an inner layer (from 30 mu m to the diffusion front) mainly composed of Fe-S, has the best wear resistance and the most sufficient adhesion among those three. (c) 2013 Elsevier B.V. All rights reserved.