Research based on ultrasonic surface treatment (UST) shows that the operation is beneficial to tribological properties and fatigue life of mechanical structures by enhancing the surface mechanical properties, such as roughness and residual stress, through changing nanostructure induced by severe plastic deformations on the surface. The amplitude of the vibration at the processing end is essential for the treatment effect. This paper presents a way to design an UST device that can control the amplitude and vibration mode.