Abstract: This paper reports a kind of linear piezoelectric inchworm motor using position-gripped ultrasonic vibrator which is a ringshaped three-pile piece construction. The position-gripped vibrator and guide shaft of the motor constitute the friction pair. When the vibrator is in the resonance state, the ratio of moving friction coeff cient to static one will decrease to-0.1. The driving voltage of position-gripped vibrator is only ±80V (Vp-p). The velocities of motor are 0-2 mm/min; the displacement resolution is 50 nm, and motor's techniques is simple.