Abstract: Based on the experimental results,the extrusion process of magnesium alloys AZ31 under different temperature field was numerically simulated by finite-element method.The effects of processing parameters on the load,strain distribution and temperature field have been analyzed.The results show that the calculated value of load is close to the measured one under different extrusion conditions,the relative error is less than 10%.Even though the billet and die were not heated,the temperature of the extruded billet was increased up to 340 ℃.If only the die was heated to 300 ℃,at the beginning of the extrusion process,the load was up to its maximum value,close to the one of extrusion process at room temperature,and then dropped greatly.The load increases obviously with the increasing of friction factor.When the billet is not heated and the temperature of die is increased gradually,the load changes little at first;and if the die temperature is over about 100 ℃,the load would begin to drop.