Dynamic transfer mechanism of the traveling wave rotary ultrasonic motor rotorstator’s contact surface was studied and the key parts stator and cone flexible rotor of ultrasonic motor were designed. Threedimensional contact model and finite element model considering the radial sliding between the rotor and the stator were established. The relation between stator surface particle that amplitude frequency characteristics, resonance speed, radial displacement of ultrasonic motor and tooth height were analyzed. Mass point radial relative displacement of contact surface between the cone flexible rotor, flexible rotor and the stator were contrasted. The cone flexible rotor was better placed on the surface of the stator tooth through its elastic deformation was interpreted. The cone flexible rotor reduces radial slip between the stator and the output efficiency of ultrasonic motor was improved. The displacement trajectory of the stator surface was synthesized in a row wave cycle. The method of the stator mass point elliptical motion drives the rotor rotation was verified. The simulation results were great significantly to the design of rotary ultrasonic motor.