Hypereutectic Al-Si alloys have received much attention in the automotive field due to their excellent heat resistance, but as the service environment of these materials becomes increasingly demanding, it is crucial to further improve the overall performance of hypereutectic Al-Si alloys. In this paper, the effects of different Cu contents and RE (La+Ce mixed rare earth) contents on the microstructures and mechanical properties of hypereutectic Al-14Si-xCu-1Ni-0.5Mg-0.5Mn-yRE alloys (referred to as Al-14Si-xCu-1Ni-yRE alloys; x=2, 3, 4 wt. %; y= 0.1, 0.3, 0.5 wt. %) in the T6 state were investigated via analytical methods, including XRD, OM, SEM, and tensile tests. The results show that the number of Cu-rich phases (e.g., Al 2 Cu and AlCuNi phases) in the Al-14Si-xCu-1Ni-0.5RE alloy increases with increasing Cu content. In particular, when the Cu content is increased to 4 wt. %, a large number of long needle-like AlSiCuNiRE precipitates even exist in the alloy, which split the matrix. The alloy elongation consequently decreases continuously, which cannot satisfy practical application requirements. When the Cu content is 3 wt. %, the Al-14Si-3Cu-1Ni-0.5RE alloy shows the best mechanical properties, the room temperature tensile strength of the alloy is 348.2 MPa, the high temperature tensile strength is 180.3 MPa, and the room temperature elongation is 1.91% . In addition, the metamorphic effect of eutectic Si in Al-14Si-3Cu-1Ni-yRE alloys is optimized with increasing RE content, but the amount of long needle-like RE-rich phase continues to increase. The room temperature tensile strength, high temperature tensile strength and room temperature elongation of the Al-14Si-3Cu-1Ni-0.3RE alloy reach 354.3 MPa, 185.5 MPa and 2.1%, respectively, when the RE content is 0.3 wt. %.