Abstract: Taking ZL105 Al-Si alloy as matrix and copper or nickel coated graphites as the reinforcement,aluminum/graphite coated composites for pistons with different contents of coated graphite were prepared by vacuum hot pressing sintering process. The microstructure, thermal and mechanical properties of aluminum/copper-coated graphite composites, aluminum/nickel-coated graphite composites and ZL105 were compared. The results show that compared with those of ZL105, when the content of coated graphite is 60 wt%, the thermal conductivity of aluminum/copper-coated graphite composite and aluminum/nickel-coated graphite composite are increased by 92.83% and 69.20%, and the thermal expansion coefficient is decreased by 49.14% and 52.59%, respectively. The mechanical properties of aluminum/nickel-coated graphite composites are better than those of aluminum/copper-coated graphite composites, and the comprehensive mechanical properties of aluminum/40 wt% nickel-coated graphite composites are the best. At this time, its hardness, bending strength and compressive strength are 100.66 HV, 109.24 MPa and 297.44 MPa respectively, compared with those of ZL105, the hardness is increased by 6.86%, bending strength and compressive strength are decreased by 9.27% and 8.48% respectively.