Abstract: Multilevel Flow Models（MFM） is a goal-oriented system modeling method.MFM explicitly describes how a system performs the required functions under stated conditions for a stated period of time.This paper presents a novel system reliability analysis method based on MFM（MRA）.The proposed method allows describing the system knowledge at different levels of Abstraction which makes the reliability model easy for understanding,establishing,modifying and extending.The success probabilities of all main goals and sub-goals can be available by only one-time quantitative analysis.The proposed method is suitable for the system analysis and scheme comparison for complex industrial systems such as nuclear power plants.