Chip　scale　package　(CSP)　as　an　advanced　technology　has　been　applied　to　LED　lighting　devices,　besides　electromigration　(EM)　in　CSP　under　high　current　density　has　become　a　critical　reliability　issue　for　the　future　high　density　microelectronic　packaging.　In　this　paper,　the　thermal-electric-mechanical　coupled　analysis　is　performed　by　the　flip-chip　CSP　LED　multi-physical　finite　element　model.　Based　on　the　atomic　flux　divergences　(AFD)　method,　the　position　of　void　formation　in　the　solder　joints　is　predicted　subsequently.　Influences　of　the　ambient　temperature　and　applied　current　on　the　EM　failure　life　of　LEDs　are　investigated　finally.