Abstract: The dynamics model of disordered cyclic periodic piezoelectric smart structure is established through the finite element method. The active vibration control of the structure is studied in a modal space by applying Linear Quadratic Regulator control method. In terms of a typical example, the dynamic characteristics and vibration control under a small disturbance are investigated. Results show that the small disorder of weak coupling cyclic periodic structure can induce remarkable vibration mode localization, and the ratio of the amplitude of a perfect structure to that of a disordered structure is about 30%. The piezoelectric smart structure has a good effect on vibration control, and the localization of vibration modes must be considered seriously in the active vibration control of the kinds of structure.