Abstract: The effects of alloying elements Ag and Cu on the melting properties,wettability,spreadability,microhardness and microstructures of Sn-40 Bi solder alloy were studied by DSC,microhardness tester and SEM. The results show that with the increase of Ag and Cu content,the melting range of the solder decreases,the wetting spreading area and Vickers hardness increase,and the Bi phase in the soldered joint is refined.