Abstract: When a certain amount of iron is added to the light aluminum alloy, the tensile strength of the alloy increases and the plasticity decreases. The modification treatment was carried out by adding a small amount of the scandium and zirconium to the aluminum alloy. The long needle Al₃Fe phase in the alloy microstructure is smaller and has a tendency to grow into free dendritic phases. The outline of Al matrix in the alloy is more clear and the microstructure is evenly refined.The improved microstructure improves the comprehensive mechanical properties of the alloy. The tensile strength of the alloy reaches 152.5 MPa, which increases by 55% compared with that of the alloy before modification. And the elongation rate is also slightly increased. At last, the effects and refinement mechanism of scandium and zirconium metamorphism on the crystallization conditions of each phase during solidification were analyzed.