In this study, the effect of the addition of trace 0.1 wt.% Y element on the grain refinement and mechanical properties of cast Al-2.2Li-1.5Cu-0.5Mg-1Zn-0.2Zr-0.2Sc alloys in as-cast and heat-treated states by centrifugal casting was investigated. The results show that the addition of 0.1 wt.% Y element to Al-2.2Li-1.5Cu-0.5Mg-1Zn-0.2Zr-0.2Sc alloys is able to enhance the nucleation temperature of the Al₃(Sc, Zr) phase, leading to the preferential precipitation of the Al₃(Sc, Zr) phase. And increases Al₃(Sc, Zr) phase precipitation density in the matrix. Al₃(Sc, Zr) phase also as a heterogeneous nucleation site in the α-Al matrix to promote nucleation, therefore, the addition of Y element significantly refines the alloy grain size. The addition of Y element changes the precipitation phase characteristics at the grain boundaries in the as-cast state of the alloy. This transforms the initially continuous and coarse strip-like distribution of secondary phases at grain boundaries into a discontinuous dot-like and rod-like distribution, with smaller size and greater quantity. After 175℃/10h aging treatment, the Al-2.2Li-1.5Cu-0.5Mg-1Zn-0.2Zr-0.2Sc-0.1Y alloy achieves an ultimate tensile strength of 412 MPa and an elongation of 6.3%. Compared to the alloy without Y, the tensile strength and elongation are increased by 16.1% and 53.7%, respectively.