In the reliability evaluation of engineering, Markov method has limitations in the life distribution of the sustems elements, while Monte-carlo method has limitation in simulation results with random defects. The uncertainty of the life distribution of the system’s elements affects the validity and accuracy of the reliability evaluation. Reliability assessments were applied in FYXF-03 dynamotor prime mover simulation system by using method of repairable systems under maintenance after failure (Rss) and Weibull model. The results are precise in this method. A useful reference is provided for making plans for equipment repair and maintenance as well as the selection of components.