The piezoelectric actuator is often used to adjust the length of optical cavity in the cavity ringdown spectroscopy for the trace gas analysis. In order to improve the precision of the actuator, a PI model is used to establish the hysteresis model of the actuator aiming at the hysteresis nonlinearity, and the least square method and gradient descent method are used to identify the model parameters, meanwhile, the parameters were identified respectively in the rising and falling process due to the asymmetric of hysteresis.The results show that,comparing to the least square method, the parameters identified by the gradient descent method can reflect the hysteresis better, and the average absolute error decreased by 67.6%. A compounding control method based on the inverse PI model is designed and verified experimentally, and the online parameter identification is adopted to update the model parameters at realtime. The results indicate that, under the sine and triangle signals, the average tracking errors of the actuator are 0.035 μm and 0.028 μm, and the proposed method can improve the positioning accuracy effectively.