The Mg-22Nd-15Al-8Zn-1.5Y alloy was prepared by vacuum arc remelting (VAR) process. Then, taking magnesium alloy as the based material, Mg-Nd intermediate alloy was added to the magnesium alloy matrix by extrusion process, and the influences of extrusion pass on the microstructure and mechanical properties of Mg-22Nd-15Al-8Zn-1.5Y alloy were analyzed. The results show that when the extrusion pass reaches five, no large grains are observed in the magnesium alloy microstructure, and many small second phase particles are generated. After many times of extrusion deformation treatment, obvious plastic flow appears in the extrusion direction, and the structure with obvious fiber shape is formed. Many small Mg-Nd intermediate alloys are formed in the grain boundary region of the alloy, which are in the form of clusters and can exert a good pinning effect on the grain boundary and significantly inhibit the dislocation movement to obtain higher mechanical strength. After five passes of extrusion, the tensile strength of specimen increases to 322 MPa, the elongation becomes 7.3%, and the better mechanical properties are obtained. During the extrusion process, some intermediate alloy particles are broken and nucleated at the position of high density dislocations to inhibit the growth of recrystallized grains.