The 40%SiC/5%Gr/Al composites with various-sizes graphite addition were fabricated by squeeze casting technology, and their friction and wear properties were investigated. Results showed that after the addition of graphite the friction coefficient of composites decreased and the wear resistance increased by 170 to 340 times. In addition, wear resistance was improved with increasing of graphite particle size, which is attributed to the enhancement of integrity of lubrication tribo-layer composed of a complex mixture of iron oxides, graphite as well as fractured SiC particles and some fine particles containing aluminum.