In order to produce aluminum alloy pipe on 45MN reverse extruder smoothly and reduce damage of the die axis. By analyzing the structure of the die axis, establish finite element model of the die axis using SolidWorks software and make finite element analysis using ANSYS software on it. thus, come to the work stress and displacement distribution nephogram when the die axis of extruder is working. After analysis of the variation law of stress and displacement in distribution nephogram, the weakest parts of the die axis can be located when stress deformation occurs and its stress variation law when working can be found. All these work provide important theoretical basis for control range of extrusion pressure and further structure optimization of die axis of the extruder in practical production.