Abstract: The microstructure and mechanical properties of Al-6.5Mg-1.5Si alloy by extrusion casting at different pressures (60-150 MPa) and pressure speeds were investigated by OM, SEM, tensile test and fracture morphology observation.The results show that the microstructure of as-cast Al-6.5Mg-1.5Si alloy is mainly composed of α-Al and eutectic Mg₂Si.With the increase of extrusion pressure, the α-Al grains and eutectic Mg₂Si phase in the alloy microstructure gradually refine, α-Al dendrites gradually decrease, and the density of the alloy gradually increases.With the increase of squeeze casting pressure, the tensile strength and elongation of the alloy gradually increase, but the increase gradually slows down.The pressure speed has little effect on the mechanical properties of Al-6.5Mg-1.5Si alloy.The tensile strength and elongation of Al-6.5Mg-1.5Si alloy obtained by extrusion casting at 150 MPa and 0.3 m/s reach the maximum values, which are 257.6 MPa and 6.2%, respectively.