Abstract: The microstructure of hypo-eutectic Al-Si alloy with Si content of 10.5% was modified by Sr modification to refine the structure of eutectic silicon, and Cu,Ni,Zn, Mg and other multi-alloying and heat treatment were carried out to improve the strength of the alloy. The results show that the eutectic silicon in the alloy can be changed from coarse acicular to fine and diffuse fibrous by adding 0.06% Sr. Adding 3.5% Cu,1.0% Ni,1.0% Mg, 0.5% Zn and other elements for multi-alloying,0.06% Sr modification treatment, and then solid solution 520℃ for 6 h and aging 185℃ for 6 h treatment, the room temperature tensile strength of hypoeutectic aluminum silicon alloy can reach 347.7 MPa.