The microstructures and mechanical properties of the Mg-5Y-xMM alloys have been investigated, where MM stands for the Ce-rich misch metal. It was found that the additions of the MM led to refinement of the microstructures and improvement of the mechanical properties. The dynamic recrystallization has occurred during hot extrusion. As a result, the mechanical properties of the alloys were greatly improved after hot extrusion. It was indicated that the specimens of the extruded alloy Mg-5Y-3MM displayed a higher tensile strength, and the values of the ultimate tensile strength and yield tensile strength were 260 and 183MPa, respectively.