Ceramic particle-reinforced materials are an important part of high-performance contact materials because of the excellent performance in resistance to arc erosion. In particular, B4C is the ideal choice for the preparation of high-performance electrical contact materials because of its excellent physicochemical properties. In this paper, Cu-B4C composites were prepared by hot-press sintering technology to illustrate the arc erosion behavior of Cu-B4C composites in different atmospheres at high voltages. The erosion morphology and composition of Cu-B4C composites after erosion in air, carbon dioxide and sulfur hexafluoride atmosphere at 8kV were studied. The different erosion mechanisms of Cu-B4C composites in air, carbon dioxide and sulfur hexafluoride atmospheres were systematically discussed. The results showed that the Cu-B4C composites exhibited inhomogeneous erosion in all three atmospheres, and the erosion was mainly concentrated in the region around the B4C particles. In air, the Cu-B4C composites were most severely eroded, but showed better erosion resistance in carbon dioxide and sulfur hexafluoride. The experimental atmosphere decomposed and reacted with copper on the cathode surface at high temperatures, while B4C maintained a good structure after erosion.