Conventional　GaN-based　flip-chip　light-emitting　diodes　(CFC-LEDs)　use　Au　bumps　to　contact　the　LED　chip　and　Si　submount,　however　the　contact　area　is　constrained　by　the　number　of　Au　bumps,　limiting　the　heat　dissipation　performance.　This　paper　presents　a　flat　surface　high　power　GaN-based　flip-chip　light　emitting　diode　(SFC-LED),　which　can　greatly　improve　the　heat　dissipation　performance　of　the　device.　In　order　to　understand　the　thermal　performance　of　the　SFC-LED　thoroughly,　a　3-D　finite　element　model　(FEM)　is　developed,　and　ANSYS　is　used　to　simulate　the　thermal　performance.　The　temperature　distributions　of　the　SFC-LED　and　the　CFC-LED　are　shown　in　this　article,　and　the　junction　temperature　simulation　values　of　the　SFC-LED　and　the　CFC-LED　are　112.80°C　and　122.97°C,　respectively.　Simulation　results　prove　that　the　junction　temperature　of　the　new　structure　is　10.17°C　lower　than　that　of　the　conventional　structure.　Even　if　the　CFC-LED　has　24　Au　bumps,　the　thermal　resistance　of　the　new　structure　is　still　far　less　than　that　of　the　conventional　structure.　The　SFC-LED　has　a　better　thermal　property.　©　2013　Chinese　Institute　of　Electronics.