Semi-infinite slender beams were analyzed with the theory of elastodynamics, conditions for large amplitude of slender beams were calculated. Based on the conditions, a linear traveling-wave Ultrasonic Motor(USM) was developed. Vibration of the stator of USM was analyzed based on consideration of traveling-wave reflection. With the help of simulation, it was shown that the reflectedwave exhibits a great influence on drive characteristics of USM. A series of experiments proved the validity of the conclusions.