Abstract: To determine the deformation parameters of AZ31 magnesium alloy, the hot deformation behavior of the alloy was investigated by hot compression testing on a Gleeble-3500 stimulator. The principle of dynamic material modeling was used to develop the hot processing map. There is a dynamic recrystallization peak zone in the processing map at temperatures from 380 to 400℃ and strain rates from 3 to 12 s^-1, and the efficiency of power dissipation is more than 30%. A fine equiaxed grain size of 2.3 μm could be achieved when differential speed rolling is processed in this region. The tensile strength is 322.7 MPa and the elongation is 19.6%. At strain rates of 15 to 50 s^-1, there are two flow instability zones:at temperatures of 250 to 300℃ the ductility of the alloy decreases obviously, but at temperatures of 350 to 400℃ the alloy has a mischcrystal structure.