The maintenance became one of the strategic industrial functions. Far from being stabilized today, it progress by introducing the new management methods and the technological development of the production equipments, in particular in the measurement and the control operation. All these factors modify the organization modes of the maintenance function, which converges more and more towards a cooperative approach. It will absorb a big part henceforth, and subsequently, will require a rigorous modeling allowing its future implementation. In this fact, we propose the specification of a workflow model to assist the cooperative maintenance. It main aim, will be to coordinate the interactions between the various intervening actors in the maintenance process.