Abstract: A trace amount of zirconium was introduced into the as-cast AlSn6Cu alloy by adding with Al-5Zr master alloy, and the effect of zirconium content (0-0.25%, mass fraction) on the microstructure and mechanical properties of the alloy was investigated. The results show that the addition of zirconium element had an obvious effect of grain refinement, and the grain size could be reduced from 1 450 μm to 280 μm by adding 0.25% zirconium. With the increase of zirconium content, the microstructure of the alloy underwent the transformation from dendritic to degenerated dendritic or petal-like, and then to near-spherical forms; the morphology of β-Sn phase changed from granular to vermicular, and then to reticular. The tensile strength of the alloys with zirconium was lower than that without zirconium. But with the increase of zirconium content, the tensile strength of the alloys with zirconium increased gradually and finally tended to be stable. The variation trend was the result of competition between fine-grain strengthening and grain boundary weakening produced by β-Sn phase. With the increase of zirconium content, the hardness of the alloy increased first and then decreased.