In order to improve the performance of linear ultrasonic motor， the topological structure of plate linear piezoelectric oscillator is designed by topology optimization method. First of all， the topology optimization analysis of the prototype is carried out without changing the geometric size of the motor， and then the modal analysis and harmonic response analysis of the prototype and topology optimization motor are carried out. Finally， the mechanical properties of the prototype and topology optimized motor are tested. It can be obtained that the maximum output force of the prototype is 1.5 N， the maximum output force of the topology optimization motor is 2 N， and the output force is 33% higher than that of the prototype. When the peak of excitation voltage is 400 V， the maximum no-load speed of the prototype is 410 mm/s， and the maximum no-load speed of the topology optimization motor is 460 mm/s， which is increased by 12%. The results show that the performance of ultrasonic motor is significantly improved after topology optimization.