Abstract: The asymmetric extrusion deformation process of AZ31 magnesium alloy was simulated by Deform 3D software.The results show that the material flows asymmetrically into the extrusion channel by setting the flow distance of different horizontal lengths, and then the asymmetric shear deformation is formed.The asymmetric distribution of strain and stress concentration occurs, and the grain of the material is deflected along the shear plane, and the high performance magnesium alloy billet with fine grain and weak texture is obtained.