A spherical ultrasonic motor with synchronous centering structure was proposed, and the mathematical model of driving moment of the motor is established. The emphasis was focused on the structural optimization design of the traveling wave type stator. The modal analysis and harmonic response analysis of the stator were carried out by ANSYS. The optimization variables of structural parameters were determined through the sensitivity analysis. The response surface model of design space was established by taking the maximum frequency difference between the working mode and the disturbing mode and the maximum stator surface amplitude of the stator surface as the optimization target. The multi-objective genetic algorithm(MOGA) was used to optimize the solution to obtain the Pareto frontier, and the final structural parameters were determined and the fabricated stator was tested through the fixed and swept frequency experiments. The test results showed that no disturbing mode was generated within the range of ±2 kHz of the working mode frequency of the optimized stator, and the points on the surface of stator under the two phase standing waves had high vibration amplitude, which met the operating requirements.