Abstract: Living probability safety analysis (Living PSA) technology, which is used to get accurate state of nuclear power plant, is attractive for the nuclear power owner and nuclear safety authority. On the basis of the binary decision diagram (BDD) study and the experience in the development of NFRisk code, the basic concept of BDD, the sorting strategy of basic event and the strategy in fault tree conversion to BDD were introduced. These strategies have already used in the platform NFRisk, and the performance is excellent.