Abstract: Routing flexibility is a desirable and important characteristic in FMS, but it complicates the scheduling and control of the system. Addressing the deadlock avoidance, this paper discusses the modeling problem with multirouting and a Petri net model, called colored resource-oriented Petri net (CROPN), is developed. This model not only describes the dynamic resource competition very well, but exactly describes the job flow in the system. We will present the necessary and sufficient conditions for deadlock-free operation by using this model.