Abstract: Aiming at the fault tree generated from UML activity diagram which can only reflect the behavior stream fault and can’t reflect the static fault,a method was proposed by using activity diagram combined with class diagram.On the basis of the original activity diagram,class diagram is used to describe the system static state information,designing transformation rules from activity diagram and class diagram to the fault tree model to transform the activity diagram dynamic behavior information and class diagram static state information into fault node elements.Based on the transformation rules,the algorithm is designed to reversely traverse activity diagram and class diagram to top-down generate fault tree.Modeling to generate fault tree indicates that the fault tree generated by UML activity diagram combined with class diagram model can reflect the system behavior fault information and static state,providing a new effective way in the generating the fault tree.

Key words: UML model,UML activity diagram model,UML class diagram model,Fault tree