The chaotic behavior of fractional-order Chen system was analyzed by giving the diagram of Lyapunov exponents and bifurcation diagram with variation of system parameters,which showed the chaotic characteristics of the system from numerical analysis point of view.After that,based on a design method for synchronization of chaotic system by using observers,a synchronization control scheme for the fractional-order Chen system was presented,and the effectiveness of the synchronization control was then proved thr...