Abstract: ZA91 D porous magnesium alloy with MgCO₃ as foaming agent was prepared by melt foaming method, and the effects of different foaming temperatures (680℃, 700℃, 720℃) on the microstructure, porosity, true density and hardness of the samples were studied. The results showed that with the increase of foaming temperature, the mesh structure of the beta phase started to break and porosity showed a trend of increase, but the average pore size decreased gradually; under different foaming temperatures, the porosity of porous AZ91 D magnesium alloy remained roughly between 37%~50%, true density ranged between the 0. 9~1. 9 g/cm³; when the foaming temperature was 720℃, the pore distribution of the obtained porous sample was more uniform, and the porosity was the largest; with the increase of the foaming temperature, the hardness of the alloy decreased, but slightly.