The microstructure and mechanical properties of as-extruded Mg-5Li-3Al-2Zn-xY alloy were investigated by optical microscope, scanning electron microscope, and X-ray diffraction. The results show that the grains of the alloy were refined due to the dynamic recrystallization, and the AlLi phases were broken and distributed along the extrusion direction during the extrusion process. The AlLi phase disappeared when the Y content increased to 2.0wt%. The highest tensile strength of the alloy reaches 326.3MPa after extrusion. Fine grain strengthening and secondary phase strengthening are the two dominant factors for improving the ultimate strength of the alloy. The effect of secondary phase strengthening is determined by the content, size and distribution of Al2Y