Abstract: The microstructure and mechanical properties of Mg-6Al-xZn alloys were investigated by means of optical microscope,universal tester,X-ray diffractometer,electron probe microanalyzer and scanning electron microscope.The results indicate that the microstructure of Mg-6Al-xZn alloys with different Zn contents was mainly composed of α-Mg,β-Mg17Al12 phase and τ-Mg32(Al,Zn)49 phase.With the increasing of Zn content,the amount of the second phase in the alloys gradually increased and the grains were refined.The Mg-6Al-6Zn alloy had the highest tensile strength at room temperature and the highest toughness.When the content of Zn was more than 6wt%,the universal mechanical properties of the alloy decreased with the grain size increasing.