Abstract: The luminance gain of the image intensifier is affected by environmental temperature and humidity during storage and use; however, the influencing patterns remain unclear. In this study, a wet and hot environment test platform based on the principle of luminance gain testing was developed. The luminance gains under different temperature and humidity conditions were tested, and the effects of temperature and humidity on the luminance gain of the image intensifier were studied. The experimental results showed that the luminance gain of the image intensifier declined significantly in high temperature and high humidity environments (temperature: 26.9℃ relative humidity: 81%), compared to room temperature environment (temperature: 20.4℃, relative humidity: 59%), and the decrease rate was approximately 13%. The results provided a verification method for environmental adaptability and reliability assessment of image intensifiers in humid and hot climatic environments.