The degradation mechanism of high power InGaN/GaN blue light emitting diodes （LEDs） is investigated in this paper. The LED samples were stressed at room temperature under 350-mA injection current for about 400 h. The light output power of the LEDs decreased by 35% during the first 100 h and then remained almost unchanged, and the reverse current at-5 V increased from 10^-9 A to 10^-7 A during the aging process. The power law, whose meaning was re-illustrated by the improved rate equation, was used to analyze the light output power-injection current （L-I） curves. The analysis results indicate that nonradiative recombination, Auger recombination, and the third-order term of carriers overflow increase during the aging process, all of which may be important reasons for the degradation of LEDs. Besides, simulating L-I curves with the improved rate equation reveal that higher-than-third-order terms of carriers overflow may not be the main degradation mechanism, because they change slightly when the LED is stressed.
