This paper investigated the volume fraction effect of micro-sized SiC on the tribological behavior of SiCp reinforced AZ91D Mg-based metal-matrix composites (MMCs). The Mg MMCs were prepared by the melt-stirring technique for wear tests. The hardness and coefficient of friction of Mg MMCs increase as increasing volume fraction of SiC particle in MMCs. The SiCp/AZ91D MMCs exhibit superior wear resistance under lower and moderate sliding condition. However, the effects of the SiC particle reinforcements on wear resistance are not as conclusive under severe sliding condition (50N-1500 rpm for all vol.% of MMCs, 50N-1000rpm for 3 vol. % MMCs), since the matrix of MMCs were softened at elevated temperature under such severe condition. However, the incorporation of SiC particles could enhance the wear resistance of AZ91D matrix alloy for most of the sliding conditions.