The invention, which belongs to the field of LED photoelectric detection, discloses a method for characterizing a junction temperature of an AlGaInP-based LED by using a volume of relative spectral distribution rotation around a Y axis by starting with a 380-nm wavelength. An AlGaInP-based LED is driven to emit light under small currents; a spectrum analyzer measures relative spectral distributionof the AlGaInP-based LED under different temperature conditions and the volume of relative spectral distribution rotation around a Y axis by starting with a 380-nm wavelength is calculated, so that avariation coefficient of the volume with the junction temperature is obtained; and according to the coefficient, a junction temperature of the AlGaInP-based LED under a to-be-measured condition is measured by combining the relative spectral distribution rotation volume at the known junction temperature. Because of the low bandwidth and measurement accuracy requirements by the relative spectral distribution rotation volume, measurement can be completed by using a common spectrograph with low costs; the multi-times measurement stability and accuracy are high. Moreover, the measurement method issimple and is easy to operate; and the LED is not in contact during the measurement process. The application range is wide.