High-power blue light-emitting diodes were biased by negative Human-Body-Mode electrostatic discharge(ESD) with -200, -400, -600, -800, -1100 and -1500 V. The electrical and optical parameters of the LED were measured before and after ESD stressing. The failure mechanisms resulted in by ESD stress were analysised after each ESD stress. The LED had evident soft breakdown due to the generation of defect in active region and cladding layers after ESD stressing at -200, -400, -600 and -800 V. However, when the device was biased to -1100 V and -1500 V, high leakage current of the LED appears and 50% degradation of light output than before stressing. The reason is the generation of melting thread in active region that made LED cannot emit light. In addition, a simple and effective protection circuit for ESD is proposed.