Abstract: For the changing risk of the petrochemical device， the node state trend expression form of the petrochemical device BN(Bayesian network) topological structure is given based on general set pair analysis(GSPA) theory and BN， the node state trend calculation model of the petrochemical device BN topological structure is proposed， the node state trend grade of the petrochemical device BN topological structure is discussed， and the node state trend grade is divided in the same situation. Application results show that the leaf node “the reaction fire explosion” belongs to the same situation， and the reactor fire explosion event occurrence is major in the BN topological structure of the reactor fire explosion. The intermediate node connection degree and its state trend level are obtained， and the difference change of the connection degree will have some certain impact on the corresponding node situation and the node level， even the situation is reversed， and provides the basis for the node state and its state situation analysis of BN topological structure.

Key words: general set pair analysis(GSPA), Bayesian network(BN), connection degree, leaf node, node state trend