<p>Sn-Bi eutectic alloy is used as lead-free solder in the low-temperature interconnection process for microelectronic packaging. However, its poor impact toughness limits its widespread application. To enhance the impact toughness, this study adopted an alloying approach with Sb addition, investigating the microstructure, melting point, and impact toughness of Sn-Bi eutectic alloys containing varying Sb contents (0.05 wt.%, 1 wt.%, and 2 wt.%). Experimental results demonstrated that the Sn phases precipitated first, and a large number of fine Bi phase particles within it, after adding the Sb element. Element Sb was enriched in the Sn phase, and the grains of Sn phases were refined in the alloys with Sb element, while the grains of Bi phases underwent significant coarsening. The addition of Sb element increases the peak temperature of the endothermic peak and broadens the melting range of the alloy. Furthermore, the impact toughness improved progressively with increasing Sb content, achieving a maximum enhancement of up to 22.2%. The solid solution strengthening of Sb in Sn matrix, the precipitated phase strengthening of fine Bi phase particles in Sn matrix, and the refinement of Sn grains were the primary reasons for the enhanced ductility of the alloy.</p>