Abstract:AZ31 magnesium alloy was used as the object of study to fabricate an alloy with the bimodal grain structure using single-pass hot rolling, and to explore how this structure enhances the strength and plasticity of the alloy. The results show that the formation of the bimodal grain structure is more pronounced at rolling temperatures ranging from 350 °C to 450 °C, especially under conditions of large reduction (≥40%). The optimized proportion and distribution of the bimodal grain structure play a pivotal role in simultaneously enhancing the strength and ductility of the alloy, significantly impacting the mechanical properties. The rolled sheet with the bimodal grain structure achieves an ultimate tensile strength of 258.3 MPa and an elongation of 17.1% under a rolling reduction of 40% with the rolling rate of 75 m/min and rolling temperature of 400 °C. Adjusting rolling parameters, including temperature, reduction ratio and rolling rate, is crucial for optimizing the bimodal grain structure, thereby achieving a balance between plasticity improvement and high strength maintenance.