Synchronization for fractional-order chaotic systems is the hot topic in the field of nonlinear study

but the study about synchronization methods for fractional-order chaotic systems are very rare at present.The co-coupled synchronization method of fractional-order unified chaotic systems is presented for the problem.The co-coupled synchronization theorem of integral-order chaotic systems is deduced according to Lyapunov stability theory and Gerschgorin theorem

and then the synchronization theorem of integral-order chaotic systems is expanded to fractional-order chaotic systems.Coupling coeffcients are confirmed by using the synchronization conditions of integral-order unified chaotic systems and simulation method and then the co-coupled synchronization of fractional-order unified chaotic systems is carried out.The results of study show that the synchronization study method of fractional-order chaotic systems according to the theorem of integral-order chaotic systems is an effcient analysis approach and the fractional-order unified chaotic systems can be synchronized by the co-coupled methods.