Abstract: Reliability of stabilized electro-optical sight system is important for the helicopter airborne weapon system. The concepts of military electro-optical system are presented, as well as the function and components of the helicopter airborne stabilized sight system. The reliability diagram and mathematical models of shipboard helicopter stabilized sight system are given. The factors influencing the systematical reliability and the failure modes are researched. The reliabilities of stabilized sight system structure, optics and electrics are discussed. A prediction method of reliability for stabilized sight system by computer simulation is proposed. Failure of a shipboard helicopter stabilized sight system occurred for two times during the 96 hours reliability test, which met the reliability requirement that the mean time between failures (MTBF) should be less than 32 hours. Prediction and analysis on the reliability of stabilized sight turret combined with corresponding provisions can improve the design quality and shorten the development cycle.