An active-passive method is used in discrete chaotic systems to study chaos synchronization.A discrete system is generally divided based on Lyapunov stability theory,and synchronization of discrete chaotic systems is realized.Bragg acousto–optic bistable system is taken as an example to verify the effectiveness of the method.Simulation results show that the error variable of two Bragg acousto–optic bistable systems with different initials approach zero smoothly and rapidly in a short series of time,which shows the method is effective and practical.The method is proper to any discrete or continuous chaotic systems with different initials,and it can be generally used.