Abstract: The sliding wear behaviour of Al₂O₃/Al composite prepared by Lanxide process was investigated in this paper. It is shown that micro porosities which are disadvantageous to the mechanical property of the composite can provide a better lubrication due to their oil contained and oil supplied effects. According to the SEM observation and energy dispersive X ray analyses, the influence of metal phases and porosities upon the composite sliding wear property was discovered, which leads to an initial discussion of the sliding wear mechanism of Lanxide Al₂O₃/Al composites.