Abstract: AZ91 magnesium alloy was fabricated by powder metallurgy. The effects of sintering temperature on the relative density and thermal conductivity were investigated. The microstructure of the material was observed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The result shows that the best sintering temperature is 610 12. At this sintering temperature the relative density can reach 97.4% and the highest thermal conductivity can be up to 63.1 W·m^-1·K^-1. The sintering microstructure of the alloy is composed of α-Mg solid solution matrix and β-Mg₁₇Al₁₂. The β phase exhibits two main forms, i.e., divorced eutectic 13 phase and discontinuous precipitated β phase.