The extrusion process of AZ31 magnesium alloy has been simulated. An actual experiment was also carried out and simulated by DEFORM-2D. The result shows that the simulated temperature-time curve agrees well with the measured one, indicating the good accuracy of the simulation parameters. And then a series of simulations of AZ31 extrusion were analyzed. The temperature distributions, stress distributions and extrusion loads were obtained. Matlab were used to describe the relationship among them in four-dimensional space