There is NP difficulty in the fault tree analysis.Although the present computer have had the rapid development in operating speed and memory property

difficulty exists regarding the large-scale fault tree′s analysis.The article main research NP problem processing when carries on the fault tree analysis.To solve this problem

two measures

e.g.early-stage unintersection

modularization and transfer event are used with more repeated events and transfer event with no repeated events.Thus the analysis of the fault tree can descend exponentially.