Abstract: Graphene/silicon carbide ceramic composites were prepared by pressureless sintering silicon carbide powders with addition of 1wt%-5wt% graphenes at 2 190℃ for 1 h. The effects of graphene addition amount on the phase composition, density and mechanical properties of the composite were studied. The results show that the composite was composed of silicon carbide phase and small amount of graphite phase. With the increase of graphene addition amount, the density of the composite decreased, the relative density changed little, the bending strength and fracture toughness increased first and then decreased, and the hardness decreased. When the mass fraction of graphene was 3%, the bending strength of the composite was 395 MPa, the hardness was 89 HRA and the fracture toughness was 6.0 MPa·m^1/2; the comprehensive mechanical properties were the highest.