Mg-Zn-Ca-Mn matrix composites reinforced with two volume fractions (1 and 3vol.%) of SiC particles (1μm) were fabricated by semisolid stirring assisted ultrasonic vibration method, and then extruded at 350℃ with the extrusion ratio of 15:1. The microstructure of materials was examined by optical microscopy (OM) and scanning electron microscope (SEM) and transmission electron microscopy（TEM）. The microstructure analysis showed that the relative uniform SiCp distribution and the refined grain were obtained in the 1vol.% SiCp/Mg-Zn-Ca-Mn and 3vol.% SiCp/Mg-Zn-Ca-Mn composites during the extrusion. The introduction of SiCp could contribute to improve the 0.2% yield strength and ultimate tensile strength. Both of the yield strength and ultimate tensile strength increased with the increase of SiCp content.