Abstract: SiC MOSFET has become a promising device with high power density and efficiency due to its excellent material properties. The device junction temperature is a key indicator for evaluating operating reliability. A non-contact online junction temperature detection method based on the electroluminescence effect of the SiC MOSFET body diode was proposed. First, the principle of electroluminescence of SiC MOSFET body diode was analyzed and the spectral characteristics of electroluminescence were studied. Three temperature sensitive optical parameters which could be used for junction temperature measurement were analyzed and compared. Secondly, the dynamic extraction of the junction temperature was realized by detecting the light intensity of the luminous peak with a negative temperature coefficient and the conduction current of the SiC MOSFET body diode. The detection resolution reached 3.1mV/℃. The feasibility of this method was verified in the Buck circuit, and the detection error was within ±3℃. This method was based on the electroluminescence detection of the SiC MOSFET body diode, which had the characteristics of inherent electrical isolation and was especially suitable for the non-contact junction temperature detection of SiC MOSFETs in high voltage applications.