The aim of this study was to prepare a functionally graded material using centrifugal casting process and study the effect of process parameters (the rotational speed of casting mold and overheating temperature) on the microstructure of a hypereutectic( Al-23%Si) alloy. The melt was overheated to( 800,900) Cº and poured in the centrifugal casting mold preheated to (100) º C ,and rotated at different rotational speed (765,840,1043,1712,1878) r.p.m . The microstructure observation showed that the increasing of overheating temperature will increase the average volume fraction of primary silicon and decreased the grain size of silicon. Increasing mold rotational speed will increase the average volume fraction of primary silicon in the inner layer of cylinder and decreased it in the intermediate and outer layer of cylinder. Increasing mold rotational speed will also decreased the grain size of primary silicon. The results of wear tests showed that the maximum wear resistant was found in the inner layer of cylinder produced using rotational speed (1878) r.p.m and pouring temperature (800) º C, minimum wear resistant was found in the intermediate layer of cylinder.