This　study　focuses　the　electromigration　behavior　of　the　particle-reinforced　lead-free　composite　solder.　The　nano-structured　cage-type　polyhedral　oligomeric　silsesquioxane　(POSS)　particles　were　used　as　the　reinforcements　to　fabricate　the　SnBi-based　composite　solders.　In　the　experiment,　the　as-reflowed　one-dimensional　composite　solder　joints　were　stressed　with　current　density　in　the　magnitude　of　10(4)A/cm(2)　at　25　degrees　C.　The　surfacial　evolution　and　interior　microstructure　were　observed　and　analyzed.　The　results　show　that　the　electromigration　behavior　was　restricted　significantly　in　composite　solder　joints　with　POSS　particles,　compared　to　that　in　eutectic　SnBi　solder　joints.　After　336　h　current　stressing,　only　few　changes　occur　at　the　surface　of　such　composite　solder　joints　and　the　total　thicknesses　of　the　accumulative　Sn　and　Bi　layers　at　the　interfaces　are　thinner　than　those　formed　in　SnBi　solder　joints.　It　can　be　concluded　that　POSS　particles　can　effectively　inhibit　the　mass　transportation　in　the　solder　joints　under　current　stressing.