Magnesium matrix composites reinforced with 4% and 8% （in volumetric fraction） Al3Ti particles were fabricated by melt casting process. Microstructure, phase constituent, relative density, hardness and wear resistance of the composites were investigated. The results reveal that dense structure in the composites can be observed, and in-situ fine and spherical Al3Ti phase is uniformly distributed into the matrix alloy with the compact bonding. With increasing in volumetric fraction of Al3Ti phase, relative density is decreased and hardness is increased in the composites, however, wear resistance of the composites is slightly deteriorated. In addition, hardness and wear resistance of the Al3Tip/AZ91D composites are superior to those of the AZ91D alloy.