The　effects　of　Si,　Cu　and　Ti　on　the　microstructure　and　properties　of　cast　hypoeutectic　Al-Si　alloys　were　studied　by　orthogonal　test.　The　results　showed　that　the　as-cast　alloy　was　mainly　composed　of　α(Al),　eutectic　Si,　θ-Al2Cu,　Q-Al5Cu2Mg8Si6　and　Π-Al8Mg3FeSi6　phases.　After　heat　treatment,　the　θ-Al2Cu　phase　precipitated　more　well-distributed,　and　the　Π　phase　transformed　into　β-Al5FeSi(Cu)　phase.　The　mechanical　properties　test　of　cast　Al-Si　alloy　after　element　regulation　and　T6　heat　treatment　showed　that　when　Si　content　was　9%,　Cu　content　was　1.5%,　Ti　content　was　0.1%,　the　strength　and　plastic　matching　of　aluminum　alloy　treated　with　T6　(solution　holding　at　520　℃　for　5　h　and　aging　at　180　℃　for　4　h)　was　the　best.　The　tensile　strength　and　elongation　of　the　alloy　were　422　MPa　and　6.2%,　respectively　at　room　temperature,　and　the　high　temperature　tensile　strength　and　elongation　of　250　℃　for　1　h　were　215　MPa　and　9.6%,　which　provides　a　certain　theoretical　guidance　for　the　application　and　development　of　cylinder　head　materials.　©　2024　Chinese　Mechanical　Engineering　Society.　All　rights　reserved.