The flexible clamping component is used to support the stator of linear ultrasonic motors (LUM). It distinctly improves the vibration characteristics of the motor and simplifies the structure, nevertheless brings the mechanical drift phenomenon. In order to improve the positional accuracy and structural stability of the V-shaped LUM, this paper studies the mechanical drift mechanism of the LUM with clamping component. Mechanical model of the motor with flexible clamp which occur mechanical drift is established, and the mechanism as well as control methods are analyzed. Based on the model, the mechanical drift experiments of clamping components with different stiffness are carried out. The experimental results show that the mechanical drift is obvious when the stiffness of the two flexible clamps are different, while the mechanical drift hardly occur when using the clamping components with tremendous tangential stiffness. Therefore, a kind of straight beam clamping LUM is proposed. The research indicate that the new motor has little mechanical drift, better running performance and higher structural stability, which can be used in the precision positioning of the mechanical devices.