In this study, the influences of Ag addition to Sn-58Bi solder on SnBi/Cu interfacial reaction and fracture behavior of the aged SnBiAg/Cu solder joints were investigated. The results reveal that the Ag element in the solder can diffuse into the Cu substrate during the soldering and aging process, forming a Cu-Ag alloy layer around the joint interface. The Bi segregation was not observed at the aged SnBiAg/Cu interface, and the embrittlement will not occur at the aged SnBiAg/Cu solder joints once the Bi segregation was restrained.