Larger control authority can be achieved by applying higher electrical field to piezoelectric actuators. This, however, will cause significant nonlinearities, such as high order relation between actuation strain and applied field and material hysteresis, in the piezoelectric material. The present paper is on the development of a nonlinear structural control law using piezoelectric material with high order nonlinearity. Analytical and experimental efforts are carried out to quantify the piezoelectric nonlinearities at high field levels. A nonlinear control scheme, which is featured by a resistor/inductor shunting actuator network and a sliding mode control algorithm, is proposed for the vibration control of a generic beam structure. Because of the robust nature of the sliding mode approach, this control scheme is also capable of compensating for other nonlinearities, such as the material hysteresis.