Mg alloys are one attractive material in applications of transportations and mobile electronics due to their high specific strength compared with other structural materials. However, Mg alloys often exhibit relatively low strength and/or low surface stability, which can limit the practical application of the alloy system. In this perspective, thermo-mechanical treatments of the alloy can give enhanced materials strength, so that the application of the alloy system can be extended towards new structural parts for requiring the light nature of the alloy system. In this study, a high temperature extrusion has been carried out for the commercial Mg alloys (AZ31). The extrusion temperature and extrusion ratio critically affected the alloy strength and ductility. The texture development and alloy strengths with respect to the extrusion conditions have been discussed in terms of microstructural observations and phase analyses.