Base on the characteristic of the system, a model of FMS (Flexible Manufacturing System) is carried on in this paper by combining with the merit of OOPN (Object-Oriented Petri Nets) and UML (Unified Modeling Language). The static structure of FMS is described with UML, but for the dynamic characteristics of the system we complete with object-oriented petri nets, and then the system Petri net model was transform into the UML state diagrams and sequence diagrams according to the corresponding mapping and the transformation rule, thus we obtain a integrity model of the system while improving the reliability of the model.