The system reliability modeling and analysis is the basis of reliability allocation and prediction, fault tree analysis and reliability optimization design. A reliability modeling and analysis method for electro-optical system was introduced. For some subsystems with multiple failure modes following exponential distribution, according to the homogeneous Markov stochastic process theory, a reliability model was built using the Markov state transition diagram method. Then the analytical expression, numerical calculation method and Monte Carlo simulation method were presented. The reliability model was applied to an example analysis for power supply circuit of an airborne electro-optical system. The above methods were used to calculate, and the results were compared and analyzed, which verifies the correctness and feasibility of the proposed method.