A series of alloys were designed and prepared using vacuum melting furnace. The as-cast microstructure and phase compositions of these alloys were characterized by optical microscope, X-ray diffraction (XRD) and scanning electronic microscope (SEM). The hardness and mechanical properties of alloys at room temperature were measured as well. The results show that the addition of RE leads to the formation of intermetallic Al3La distributed within grain boundaries. The intermetallic compound with oriented structure impedes grain growth, and refines the grain. The strength and the hardness of the alloys increase with the increase of the RE content in the range of 0.2-0.8 wt %.