The influence of Ce on solid solution and aging process of AZ91D magnesium alloy was analyzed. The results showed that the decomposition of β-Mg17Al12 phase in AZ91D magnesium alloy at 420 °C could be completed within 12 h, while this process in the Ce-containing alloy required more time. In subsequent aging process at 175 °C, Ce obviously delayed the aging process of AZ91D. It was inferred that the influence of Ce on process of solid solution and aging was relative to the Ce that existed in β-Mg17Al12 phase of original structure in the form of solid solution, and the interaction of the Ce and Al was an important factor to get process of solution and aging slowly. The influence of Ce on solid solution and aging process of AZ91D magnesium alloy was analyzed. The results showed that the decomposition of β-Mg17Al12 phase in AZ91D magnesium alloy at 420 ° C could be completed within 12 h, while this process in the Ce- It was inferred that the influence of Ce on process of solid solution and aging was relative to the Ce that existed in β-Mg 17 Al 12 phase of original structure in the form of solid solution, and the interaction of the Ce and Al was an important factor to get process of solution and aging slowly.