Abstract: Mg-3Zn-xCa-ySr alloy(x=0, 0.1, 0.3, y=0.1, 0.3)was prepared by crucible resistance furnace.The effects of Ca and Sr addition on the microstructure and mechanical properties of Mg-3Zn alloy were investigated by OM, XRD and SEM.The results show that the microstructure of Mg-3Zn-0.1Sr alloy is slightly refined and the mechanical properties of the alloy greatly improve when a small amount of Ca is added.When the content of Ca reaches 0.3%, the second phase Mg₂Ca appears in the alloy, which is continuously distributed on the grain boundary, has little effect on the yield strength, and slightly reduces the tensile strength and plasticity of the alloy.When the Ca content is 0.1%, with the increase of Sr content, the grain of the alloy is refined and the second phase increases, and a new phase Mg₁₇Sr₂ is formed on the grain boundary, which inhibits the effect of fine grain strengthening, and makes the yield strength and tensile strength of the alloy change little, but the plasticity significantly improves.At this time, the comprehensive properties of the alloy are best.