Bayesian networks(BN) and fault tree analysis(FTA) were compared for safety fault analysis. According to the initiator system, a new method that used FTA & BN to perform fault analysis was proposed. The reasons causing safety fault to the igniter with the method were analysized as the non-uniform density of delay powder, the sticking of protechnic charge to the internal wall of delay tube and the failure of alarm device, etc. The corresponding solution was established at end.