Microstructure　evolution　and　temperature　distribution　of　eutectic　SnBi　solder　joint　under　high　current　density　of　1×104A/cm2　at　room　temperature　were　investigated　in　the　current　study.　With　the　increase　of　current　stressing　time,　a　continuous　Bi　segregation　layer　was　formed　and　grew　along　the　interface　at　the　anode　side,　and　a　Sn　rich　region　was　found　at　the　cathode　side.　Due　to　the　microstructure　changes　in　solder　alloys,　temperature　distribution　tended　to　be　nonuniform.　Because　of　the　aggregation　of　Bi　atoms,　which　have　higher　electrical　resistivity　and　lower　thermal　conductivity,　at　the　anode　side,　the　temperature　of　anode　was　higher　than　the　cathode.　Due　to　the　formation　of　severe　cracks　in　the　solder　joints,　the　local　Joule　Heating　effect　was　enhanced　and　the　local　temperature　was　much　higher.　It　was　found　that　the　microstructure　evolution　induced　by　electromigration　(EM)　could　alter　the　temperature　distribution.　By　using　the　infrared　microscope　to　record　temperature　in　the　solder　joint　during　current　stressing,　the　relationship　was　established　between　microstructural　changes　and　temperature　filed　in　the　SnBi　joint　under　high　current　density.　©　2014　IEEE.