Abstract: Cu-Al₂O₃ composite has excellent conductivity and mechanical properties, and it widely used in the field of wear-resistant materials. In order to further improve the arc erosion resistance of composite under the condition of electro-friction, CNTs/Cu-Al₂O₃ composites with different contents of carbon nanotubes (CNTs) were prepared by internal oxidation combining with powder metallurgy. The distribution of reinforcing phase and the interface between CNTs and matrix in CNTs/Cu-Al₂O₃ composites were observed. The conductivity and mechanical properties of Cu-Al₂O₃ composites effected by CNTs were studied. The arc erosion resistance mechanism of CNTs/Cu-Al₂O₃ composites was mainly explored. The results show that in-situ nano-Al₂O₃ particles pin dislocation, CNTs are dispersed in the copper matrix due to the regulation of CNTs distribution by Al₂O₃ particles. Compared with Cu-Al₂O₃ composites, the arc duration and energy of CNTs/Cu-Al₂O₃ composites are obviously reduced and fluctuate more stable. In the process of arc erosion, CNTs in the molten pool will float to the surface to disperse the arc and reduce the concentrated erosion area. Nano-Al₂O₃ particles can stabilize the molten pool, reduce the splash of molten droplets and the mass loss of CNTs/Cu-Al₂O₃ composites. Among them, CNTs/Cu-3.5Al₂O₃ composites with 1.2vol%CNTs has the lowest and most stable arc duration and energy. This research result provides a favorable theoretical basis for the research of ablation resistant materials.