The effects of antimony and indium addition on wettability and interfacial reaction of Sn-3.0Ag-0.5Cu lead free solder on copper substrate were investigated. The experimental results showed the melting point of solder alloy containing 0.5 wt.% In and 0.5 wt.% Sb were slightly increased about 3.66°C. The pasty range of solder alloys were increased about 6°C while the undercooling of solder alloys were decreased. The microstructures of solder alloy were contained of In and Sb consists of Ag3Sn, Cu6(Sn,In)5, SnIn, Ag3(Sn,In) and SnSb intermetallic compounds (IMCs) dispersed on Sn-rich phase. The wettability of solder alloys were improved by increasing soldering times. In addition, the thickness of intermetallic compounds (Cu6Sn5) were obviously increased with increasing soldering times.