For the traveling wave type rotary ultrasonic motor (TRUM), the contact interface of stator and rotor was modeled by a three dimensional point to point element using ANSYS. According to the characteristics of the traveling wave, two simplified models established in the space and time domain were presented . The output characteristics and losses at the contact interface were calculated from the models. The results show that the two methods are in good agreement. The preload force can be directly used as a given condition in the space domain, which is convenient to analyze the influence of preload force on TRUM. However, th e stickslip phenomenon can be analyzed in the time domain. The space domain model costs less time to be solved, which benefits integrating the model into the d esign of a complete TRUM.