Abstract: Plasma Enhanced Chemical Vapor Deposition （PECVD） SiN_x films deposited at the substrate temperatures from 20℃to 180℃and at the RF powers from 10W to 30W were investigated. With the increment of substrate temperature, the density, refractive index and Si/N ratio of SiN_x film increase, but deposition rate and H content decrease. With the increment of RF power, the deposition rate, density, the refractive index and Si/N ratio of SiN film increase, but H content decreases. Water vapor permeation （WVP） measurement shows that at the low substrate temperature such as 50℃, the moisture resistance of SiN_x films keeps quite good. It suggest that SiN_x films deposited at low tempera- ture can be applied in Organic Light Emitting Devices （OLED） packaging effectively.