The influences of different Zr/Sc ratios on the microstructural evolution and mechanical performances of Al-2Si alloy were investigated in this paper.The as-cast samples were characterized and analyzed by the scanning electron microscope (SEM) with an energy dispersive spectrometer (EDS) to indicate the refining effect of the different Zr/Sc ratios on the α-Al and Si phases in Al-2Si alloy.The results indicate that the α-Al phases are refined from coarse dendritic structure to relatively fine equiaxed grains when the Zr/Sc ratio is equal to 1∶1.Meanwhile,the eutectic Si phase in Al-2Si-0.2Zr-0.2Sc alloy is modified from the coarse plate and needle to fine fiber and partial granular structure,and the average roundness of eutectic Si is decreased by 75％ from 16 to 4.With the refinement of α-Al phases and the modification of eutectic Si structure,the ultimate tensile strength (UTS) is improved by 53％ and the elongation (EL) is increased by 64％ when the Zr/Sc ratio is equal to 1∶1.In addition,the UTS decreases and EL is enhanced with the increase of tensile temperature.Moreover,the fracture model of Al-2Si-0.2Zr-0.2Sc alloy in 250 ℃ changes into the ductile fracture.