Abstract: A series of Al-Si eutectic alloys with different contents of Cu (0.3%, 0.8%, 1.3%, 1.8% and 2.5%) and 0.3% La were investigated. The results showed that the morphology of eutectic silicon is transformed from acicular/lamellar to pointlike and short rodlike when the addition of La is 0.30%, and the alloy reaches the best modification state. With the increasing of Cu content, the number and size of Al2Cu phases, the tensile strength and hardness increase, but the elongation decreases. When the addition of Cu is 2.5%, the tensile strength, elongation and hardness of Al-12.6Si-2.5Cu-0.3La are 241.4 MPa, 4.82% and 83.9 HV, respectively, which increase 58.1%, 41.8% and 30.9%, respectively, compared with those of Al-12.6Si alloy. The mechanical properties of Al-Si eutectic alloy are improved obviously.