Abstract: The surface of graphite flakes(GFs) was coated with Si by salt bath method, and the graphite flakes/Al composites (Si-GFs/Al) were prepared by vacuum hot pressing method. 10vol% Cu mesh was added to Si-GFs/Al composites, and the effects of Cu mesh on thermal conductivity and mechanical properties were studied. The microstructure and micro interface of Si-GFs/Al composites were characterized by SEM, focusing ion beam (FIB) and TEM. The fracture mechanism of the composites was analyzed. The results show that highly clustered GFs bands have been built in the Si-GFs/Al composites after Cu mesh added. When the GFs volume fraction is 30vol%~40vol%, the thermal conductivity of Si-GFs/Al composites increases by about 20%, and the bending strength increases by more than 40%. The thermal conductivity and bending strength of Si-GFs/Al composites with 40vol% GFs both reach a satisfactory value, which are 512 W/(mK) and 127 MPa, respectively.