Abstract: This article focuses on the connection between Sn-5Sb-based solders suitable for power device interconnection and Cu-plated Ni substrates to study the effect of the addition of Cu,Ni,and Ag elements on the anti-aging performance of joints. The three kinds of Sn-5Sb-CuNiAg solders,Sn-5Sb,and SAC305 were connected to Cu-plated Ni substrates respectively,and the microstructure was compared and analyzed by SEM and EDX. The evolution of the matrix structure and compounds during the aging process of bulk solders and the evolution of the interfacial compounds with the aging time were studied. The results showed that Sn-5Sb-CuNiAg and SAC305 bulk solders were mainly bulk compounds（Cu,Ni）₆Sn₅ and granular silver-tin compounds,and Sn-5Sb solders were mainly bulk compounds（Cu,Ni）₆Sn₅. As the aging time increased,the compounds in the bulk solder became coarse. The interfacial compound layer was obviously thickened,and the compound morphology gradually changed from irregular jagged to gentle and uniform layer. The thickness of the interface compound layer of Sn-5Sb-CuNiAg solder joints was relatively thinner than that of Sn-5Sb and SAC305 soldered joints. Sn-5Sb-CuNiAg soldered joints had better thermal aging resistance. Adding 0. 5 wt% Cu and 0. 1 wt% Ni elements could inhibit the growth rate of the interfacial intermetallic compounds.