Optical interference method by Michelson interferometer was adopted to measure the nonlinear hysteresis curves of piezoelectric ceramic under constantcurrent slaving voltage.Two ways for depicting the degree of nonlinear hysteresis were put forward.The changing tendency of the degree of nonlinear hysteresis under different starting voltages and extension offset variables were further analyzed.Then,hysteresis curves of piezoelectric ceramic were measured by adding circulating voltage,and the changes of linear or nonlinear factors,which would influence piezoelectric ceramic,were also analyzed.Finally,the changing curves of sensitivity of piezoelectric ceramic were presented.