Channel　temperature　determinations　of　AlGaN/GaN　high　electron　mobility　transistors　(HEMTs)　by　high　spectral　resolution　micro-Raman　spectroscopy　are　proposed.　The　temperature　dependence　of　the　E2　phonon　frequency　of　GaN　material　is　calibrated　by　using　a　JYT-64000　micro-Raman　system.　By　using　the　Lorentz　fitting　method,　the　measurement　uncertainty　for　the　Raman　phonon　frequency　of　±0.035　cm-1　is　achieved,　corresponding　to　a　temperature　accuracy　of　±3.2　°C　for　GaN　material,　which　is　the　highest　temperature　resolution　in　the　published　works.　The　thermal　resistance　of　the　tested　AlGaN/GaN　HEMT　sample　is　22.8　°C/W,　which　is　in　reasonably　good　agreement　with　a　three　dimensional　heat　conduction　simulation.　The　difference　among　the　channel　temperatures　obtained　by　micro-Raman　spectroscopy,　the　pulsed　electrical　method　and　the　infrared　image　method　are　also　investigated　quantificationally.　©　2012　Chinese　Institute　of　Electronics.