The resonant feature of the piezoelectric resonator of ultrasonic motor is analyzed based on the COMSOL Multiphysics in this paper. The entity model of the piezoelectric resonator of ultrasonic motor has been established. The resonant frequency of the piezoelectric resonator was calculated by the simulation and the best operating frequency range of ultrasonic motor was determined. The matching method between the motor and the driving circuit was proposed. The test results showed that when an exciting voltage with the amplitude of 100 V was applied to the piezoelectric resonator, the software analysis results were basically consistent with the mathematical calculation thus indicated that the method of simulation analysis was feasible. This provides a simple calculation method for the study of the resonant feature of ultrasonic motor.