Abstract: In order to further improve the positioning accuracy of the ultrasonic motor and meet the urgent needs of the aerospace drive mechanism for high positioning accuracy, the flexible shaft is used to improve the operating stability of the ultrasonic motor. Based on the transient response characteristics of the motor, the highprecision positioning of the ultrasonic motor is realized. The ultrasonic motor has the characteristics of fast response and the possibility of achieving high positioning accuracy. However, due to the unclear stepping characteristics and large fluctuations in operation, its potential has not yet been fully utilized. To solve this problem, first explore the stepping characteristics of the ultrasonic motor to obtain the stepping law of the motor under different load torques, and then use a continuous mode and stepping mode combined control strategy to achieve the highprecision positioning characteristics of the ultrasonic motor. The results of the study show that after the flexible shaft is adopted, the stepping fluctuation of the motor is greatly reduced, the positioning accuracy of the motor can reach 0.48 ″, and the costed time is less than 1.34 s.