Thermal　feature　is　an　important　factor　of　LED.　However,　as　an　internal　parameter,　junction　temperature　cannot　be　measured　easily.　Based　on　the　LED　circuit　model,　which　is　an　ideal　diode　and　a　resistor　in　series,　a　new　model　of　LED　junction　temperature　T-j　is　proposed　in　this　paper.　Parameters　can　be　extracted　from　the　oil　bath　experiments.　In　this　way,　junction　temperature　can　be　derived.　The　accuracy　of　the　method　is　verified　through　the　oil　bath　experiments　and　optical　experiments.