Abstract: In this paper,the microhardness and continuous heating specific heat of AZ91 magnesium alloy and SiCw/AZ91 Mg composite were, determined by micro-hardometer and adiabatic specific heat measurer,respectively,and the aged microstructures were observed by SEM. The effects of aging temperature and time on the precipitation structure were analyzed. The results show that the microhardnesses of both the composite and the AZ91 magnesium alloy increased after aging processes.The specific heat curves of the AZ91 magnesium alloy are similar to that of the SiCw/AZ91 Mg composite.Only when the aging temperatures are between 200℃ and 225℃,the aging microstructures of the SiCw/AZ91 Mg composite apear, and its morphology is similar to the continuous precipitation structure.