ABSTRACTSiphon control has been utilized as a general methodology for systems of simple sequential process with resource (S3PR) deadlock systems. Although siphon control imposes additional control places on S3PR systems, it cannot guarantee that the maximum permissiveness is achieved. To solve the problem of deadlock prevention for S3PR, a new policy to design a deadlock-free supervisor with the maximally permissive system is proposed using additional transitions. Additionally, this approach can solve the problem of deadlock prevention for systems of sequential systems with shared resources (S4PR) system models.