Abstract: Two kinds of lightweight composite porous magnesium alloy are successfully prepared by selecting two different ceramic hollow spheres(the commercial alumina hollow sphere and the self-made containing silicon hollow sphere) as reinforcements and sintering at 600℃ for 3 h 20 min. The microstructures of samples were observed by SEM. It was found that an alloy phase containing MgO and Mg₂Si was formed by an interfacial reaction at the interface between the magnesium alloy and the self-made containing silicon ceramic hollow sphere. The influence of different types of ceramic hollow spheres on the apparent density, compressive strength and specific strength of samples was studied. The results show that the bulk density of the sample prepared by the commercial alumina hollow sphere is lower than that of another sample, and the average apparent density is 33.3% lower than that of the dense magnesium alloy, which is 1.20 g·cm^-3. The average apparent density of the sample prepared by self-made containing silicon ceramic hollow spheres is 16.1% lower than that of the dense magnesium alloy, which is 1.51 g·cm^-3.The compression curves of both samples have the elastic stage, the yield platform and the densification stage, which are the typical compression characteristics of porous materials. The compressive strength and specific strength of the sample with self-made containing silicon ceramic hollow spheres are higher than that of the sample with commercial alumina hollow spheres.