The influence of deformation temperature and deformation extent of magnesium alloy on plastic forming was investigated.The die and device used for the experiment,and the extrusion technique for magnesium alloy in terms of the selection of lubricant,extrusion speed,extrusion temperature and the heating of blank were described.The result indicates that preferable forming performance of magnesium alloy can be obtained under the condition of combined isothermal extrusion.Then a feasible extrusion process and technological parameters for AZ31 magnesium alloy were planned.