Abstract: A global coupling dynamic model of a temper mill system is established by using bond graph and power topo-bond graph, coupling properties are depicted and its effects are analysed. With the aid of topo-bond and its causal bar, the solution of global mathematical model of the whole system is found on the basis of finding the solution of subsystem. Therefore, mathematical model stiffness and simulation time are greatly reduced. Since the global coupling model of the whole system is highly of modularity, it can be took down or spliced conven-iently for different rolling mill systems. The study shows that simulation results of global mathematical model are much closer to experimental results than that of isolated mathematical model. The proposed method may be commonly applied to modelling and analysis of other complex electromechanical systems.

Key words: Bond graph, Complex electromechanical system, Global coupling