The purpose of this study is to prepare a high-quality Al-11Si-1.5Cu-0.3Mg casting al oy with a good combination of strength and ductility. The microstructures of as-cast al oy were tailored by employing combined additives of Al-3wt.%B reifner, Al-10wt.%Sr modiifer and trace addition of La element. By using OM and SEM, the characteristics of the morphologies of eutectic Si particles and the fracture surfaces of the al oys after solution treatment and aging treatment were measured. The mechanical properties of the al oys after single-step or two-step solution treatment were investigated by tensile testing, and the quality of casting samples were evaluated by quality index, Q. The results indicate that the al oy with substantial y modiifed microstructures displays an improvement in mechanical properties of 270 MPa in ultimate tensile strength and 6% in elongation. After an optimized two-step solution treatment of 490oC/4h+505oC/4h, the ultimate tensile strength and elongation can reach 346 MPa and 10%, respectively. Under the aging condition, the elongation maintains a relative high value of 5%together with the strength of about 400 MPa, which is the outstanding combination of strength and ductility.