Cu-coated graphite was applied to modify the interface of Cu-Ni-graphite composite used as switch slide baseplate. Up to now, interfacial characterization and modification mechanisms of Cu modified Cu-Ni-graphite composite are seldom researched. In this study, Cu-coated graphite was deposited by chemical plating, and Cu modified Cu-Ni-graphite composite was prepared by powder metallurgy. Both the microstructure characterizations of Cu-coated graphite and interfacial morphologies of the composite were investigated. Then, the comparison of mechanical properties of unmodified and Cu modified Cu-Ni-graphite composite was discussed. The results showed that the Cu coating was made of fine particles with uniform distribution and with the average thickness of 1.05 mu m. The mutual diffusion was about 2.54 mu m width at the interface. The interfacial modification mechanism of Cu coating in the composite was that the decreasing of diffusion activity both in the graphite and matrix; and the increase of diffusion driving force at the interface. The interfacial bonding method in the transition from mechanical bonding to the combination of mechanical bonding and diffusion bonding. Compared with the unmodified composite, the flexural strength raised 24.4%, and hardness increased by 9%. [GRAPHICS] .