Abstract: Al 2O 3f +C f/ZL109 short fibers reinforced hybrid metal matrix composites were fabricated by squeeze casting.The effect of Al 2O 3 fiber volume fraction on the wear resistance of the hybrid composites with a fixed carbon fiber volume fraction of 4% was investigated.The morphologies of the worn composite surfaces were observed with a scanning electron microscope. The results showed that the friction coefficient of the hybrid composites in dry sliding against SAE52100 steel increased with increasing Al 2O 3 fiber volume fraction.The combined reinforcing effect of both the Al 2O 3 and carbon short fibers led to a considerable increase of the transition load from mild wear to severe wear of the hybrid composites which rose with increasing Al 2O 3 fiber volume fraction as well.There existed a critical volume fraction of Al 2O 3 fiber below the critical load corresponding to the transition of mild wear to severe one, at which the lowest wear rate of the hybrid composites was recorded. No obvious signs of fiber detachment and peeling off were observed on the worn composite surface when the Al 2O 3 volume fraction was below the critical value 12%, while they were visible when the Al 2O 3 fiber volume fraction was above 12%. This could be attributed to the abrasive action of the wear debris originated from the detached fibers which were more liable to peel off as the Al 2O 3 volume fraction was above the critical value 12%.