The microstructural evolution and mechanical properties of Mg-6Zn-1Mn-4Sn-0.5Y wrought alloy extruded at 360 and 420℃ were investigated by optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), electron back scattered diffraction (EBSD) and tensile test. The results shown that the phase compositions of as-cast and extruded alloys were α-Mg, Mn, Mg7Zn3, Mg2Sn, and MgSnY phases. As the extrusion temperature increased from 360 to 420℃, dynamic recrystallization completed and grain growth occurred. The yield strength, ultimate tensile strength and elongation decreased from 259MPa, 350MPa and 18.3% to 239MPa, 332MPa and 12.5%, respectively. The theoretical values combined with the experimental values revealed that grain size strengthening and solid solution strengthening played the dominating role in the enhancement of yield strength.