Abstract: The method of state observer synchronization is applied to the latest model of a unified chaotic system.By designing a suitable state observer,exact synchronization of unified chaotic system with noise interference is studied.The scope of control parameters is presented,and some factors which influence synchronization performance of the system are discussed,including system parameter,noise interference,initial value and control parameter n₂.The simulation results based on Matlab 6.5 show that this method is effective.