Through the prediction based on reliability counting method, identified weak links of automatic control system, achieved the reliability modeling of marine power station and structured reliability block diagrams and the reliability mathematical models, the reliability and mean time between failures (MTBF) of marine power station are obtained under different work conditions. The marine power station reliability modeling acquired from different work conditions accords with the actual operating mode, and all these work can supply more scientific theoretical support for study on reliability of marine power station.