Cu-5.8vol.-%TiB2 composites reinforced with different sized TiB2 particles were prepared by spark plasma sintering (SPS). The arc erosion resistance was examined using a JF04C electrical contact instrument. The results indicate that the TiB2 particle size and contact currents have important effects on the material transfer mode. Both lower mass loss and relative mass transfer was observed in the Cu-5.8vol.-%TiB2 composites reinforced with fine TiB2 particles (10 um, 30 um) compared to those with coarse TiB2 particles (70 um, 110 um). The investigation and analysis of the microstructure and arc erosion mechanism show uniform distribution of fine TiB2 particles in the copper matrix can significantly improve the viscosity of the molten pool and decrease the splashing of molten Cu.