Abstract: Alumina and carbon short fibers reinforced ZL109 aluminum alloy hybrid composites were fabricated by squeeze casting.The effects of the alumina volume fraction on dry sliding friction and wear properties of the hybrid composites with the fixed carbon fiber volume fraction 4 % were investigated.The results show that the carbon fiber is of self-lubricant in a certain degree,however,the friction coefficient of the hybrid composites improves due to addition of alumina fiber and increases with the increase of alumina fiber volume fraction.The transition load from mild wear to severe wear of the hybrid composites improves markedly because of the mutual effect of alumina and carbon short fibers and increases with the increase of alumina fiber volume fraction.There exists a critical value of alumina fiber volume fraction which influences the wear property of the hybrid composites with the lowest wear rate at the volume fraction of 12 % when the experimental load is below the transition load.Dominant wear mechanisms of composites are grooving wear and delamination during mild wear.Whereas dominant wear mechanisms of matrix and composites will be shifted to severe adhesion when the experimental load is above the transition load.