Polymer light-emitting devices (PLEDs) are extremely sensitive to moisture and oxygen. Without high-performance hermetic encapsulations, the life of these devices is limited. This paper reports the lifetime characteristics of plastic PLED containing a hermetic multi-layer encapsulation by configuration of silicon dioxide (SiO2)/ silica-coated gold nanoparticles /SiO2 layer. The electroluminescent (EL) features were examined to compare the rate of degradation in the devices with the multi-layer encapsulation and the SiO 2 single-layer encapsulation. Thus, it is confirmed that the multi-layer encapsulation with passivation layer of silica-coated gold nanoparticles has an effect as encapsulation process to protect plastic PLED.