The accelerated life tests(ALTs) and degradation characteristics of image intensifier assembly(KIT-7) under low illuminance and high temperature were investigated. The accelerated life tests were carried out at $5{ imes}10^5;fc-40^{circ}C,;10{ imes}10^5;fc-40^{circ}C,;5{ imes}10^5;fc-50^{circ}C,;10{ imes}10^5;fc-50^{circ}C$ and relationship related to illuminance and temperature was used as an accelerated life test model. An ALTA program[6] was used to calculate an acceleration factor and the test of life distribution fit, and estimate three parameters of an life test model. To sum up, MTTF 10,000 h at $5{ imes}10^{-5};fc-40^{circ}C$ of image intensifier assembly was certificated.