SiON passivation layer is deposited on GaN blue LED based on Si substrate. It improves the light output power of LED by 12% and reduces the luminous decay of LED during aging efficiently. The analysis results of the samples with and without SiON passivation layer demonstrate that SiON layer can separate the epoxy from hot surface of LED during aging, which prevents epoxy resin from carbonization. In addition, the SiON layer can partly relax tensile stress of device from epoxy resin, and reduce the generation probability of non-radiation centers. Furthermore, SiON layer can reduce sidewall leakage current of LED. In a word, SiON layer can improve the stability of LED.