Abstract: The effect of Ga/Nd multi-addition on microstructure of Sn–0.3Ag–0.7Cu solder in the course of aging treatment was investigated. The results indicated that the multi-addition of Ga/Nd could significantly refine the interfacial microstructure of solder joint and inhibit the formation of intermetallic compounds after aging treatment. After aging treatment over 720 h, no evident rare earth phase Ag₃Sn was found in Sn–0.3Ag–0.7Cu–0.5Ga–1Nd solder joints, instead, new phase was formed near the interface of solder joint And the results of EDS and XRD indicated that the new phase should contain Ga₂Nd and Cu₆Sn₅. The shear force of Sn–0.3Ag–0.7Cu solder joint after aging treatment reached 90% of Sn–3.8Ag–0.7Cu solder joint.