Abstract: Five kinds of arming logic models with three independent safe devices controlling three environmental stimuluses are proposed. The context adopted Markov theory to set up different arming logical models and analyzed them. In theory, for five models of electronic safe and arming(ESA), it attained the highest safety with three safe devices and added two time windows and closed simultaneously. A comparison is made with the safety of mechatronic safety and arming adopting two independent environmental stimuluses, the inherent safety of ESA is found to be higher.