When the thyristor inverter is used as the power supply for asynchronous motors, the output voltage and current are rich in harmonics. These harmonics will have a significant impact on the operating performance of asynchronous motors, resulting in the increase of power loss and the decrease of efficiency and power factor. Although the traditional pulse width modulation (PWM) method can eliminate the influence of loworder harmonics, the overall effect is not ideal. Through the specific analysis of the influence of harmonic components on the stator and other motor parameters, the minimum total loss of asynchronous motor is taken as the objective function. Then, carrier ratio is determined according to the relationship between the variation of various loss coefficients with frequency and the number of switching times of the inverter thyristor switching element. Finally, the strategy design of general PWM is optimized. The test results show that the optimized design can effectively suppress the influence of harmonics.