The friction interface matching plays a deterministic role in the motor efficiency ,and the microcosmic contact status of friction interface should be investigated to improve the ultrasonic motor performance .The main purpose is to improve the effective output power of ultrasonic motor .Hence ,one studies the contact condition of the friction interface of the ultrasonic motor ,analyzes the micro condition of contact interface through finite ele-ment analysis ,optimizes unreasonable structures ,and compares the two different-structure ultrasonic motors through experiments .The results reflect the necessity of optimization .After optimization ,the stator and rotor de-form after pre-pressure and the contact interface of them full contact theoretically .When reaching heat balance the effective output of the motor is 37% ,and the average effective output efficiency is 2 .384 times higher than that of the unoptimized .It can be seen that the total consumption of the ultrasonic motor system decreases significantly . Therefore ,when using in certain system the consumption taken from the system will decreases largely ,especially in the system with a strict consumption control .