In this paper, a wear model is established for a V-shaped linear ultrasonic motor. The influence of the change in the dynamic friction coefficient and the roughness parameters of the contact surface of the stator/slider on the output performance of the motor is considered in this model. The wear mechanism of the motor and the variation rules of the morphology of the contact surface during the operation of the motor are studied, as well as the relation of the wear height of the driving tip with the preload force and the relation of the preload force with the resonance frequency of the stator. The accuracy of the model is verified by numerical simulation and experimental methods. A test platform for friction and wear experiments is constructed, and the wear characteristics and the output performance of the motor are tested. The obtained results indicated that the model can accurately predict the dynamic changes during the wear process and the service life and output performance of the motor.