Abstract: In this paper, nonlinear dynamic characteristics ofpiezoelectric bending actuators under strong electric field are studied.Considering nonlinear piezoelectric effect of the electrostriction andelectroelasticity, the bending vibration governing equation of thecantilever piezoelectric actuator, in which the stiffness is variable withtime, is obtained. Using the asymptotic theory of nonstationary vibrations,the dynamic characteristics of the cantilever actuator are discussed. Theproposed nonlinear model predicts the change in fundamental resonantfrequency of piezoelectric cantilever with the variation in electric field.The predicted resonance amplitude of the tip deflections of thepiezoelectric actuators, which increase with the increase in the magnitudeof the electric field, the decrease in the mechanical quality factor withthe increase in the electric field, and well agrees with experimentalresults. By comparing with predicted results, it is found that the problemof nonstationary vibration can be approximately treated as stationaryvibration under the electric field frequency varies very slowly.