The compositions of ZL101 were optimized with an orthogonal test, and the effects of the alloying elements on the mechanical properties of Al-Si alloy were analyzed. The heat treatment process of the as-modified alloy was investigated. The optimal parameter obtained was 500 ℃×5.5 h+180 ℃×5 h. The results showed that the mechanical properties of as-modified alloy were -σ-b=244.57 MPa,- δ-=5.95%, HB=75.1 under the F treatment and -σ-b=397.92 MPa,- δ-=4.68%, HB=141.2 under the T6 treatment, respectively. Compared with conventional casting aluminum silicon alloy for engine cylinder head, the as-modified alloy shows excellent mechanical properties.