Magnesium matrix composites SiCp/ AZ61 reinforced with SiC particulates was fabricated by stirring-melt casting technique. The damping properties of the composites have been studied with dynamic mechanical thermal analysis and micro-structural observation. The results show that matrix grains introduced SiC particulates were refined obviously at room temperature and the properties of SiCp/ AZ61 composites were improved comparison to AZ61 alloy. Meanwhile, the improvement of damping properties can be explained by G-L dislocation pinning theory. The damping characterization is explained with the increasing of quantities of the grain-boundaries for the introducing of SiC particles and the ease of interface slipping in temperature.