Abstract: The effects of two aluminum matrix alloys,pure A1 and Ly12,on the mechanical properties of graphite fiber reinforced aluminum composite were investigated,and the mechanisms of effects were also studied.The results show that matrix alloys have a significant influence on the inerfacial state as well as the composition and distribution of the phases in the matrix,and finally on the properties of the Gr/Al composites.LY12,Compared with pure Al,deterioated greatly the tensile strength of the composites.