Mg-3Y-0.6Zr-X alloys was prepared by mixed gas protection . The microstucture and mechanical properties of the alloys adding Sm、Ce were analyzed by means of optical microscope(OM), X-ray diffraction analysis (XRD), scanning electron nicroscopy (SEM) , and drawing machine . The results show that the addition of Ce and Sm refines the alloy grain and makes structure more uniform . The tensile strength of alloy increased by 48% with the addition of Sm ; The mechanical properties of the alloy is worsen with the composite addition of Sm and Ce . The yield strength is improved markedly after adding Zn .