When permanent magnet synchronous motor (PMSM) is driven by the inverter, the loss of motor can be greatly increased due to the influence of high content of time current harmonics generated by inverter, which can seriously affect safety and stability of motor operation. However, the loss suppression effect brought by traditional method of optimizing the structure of motor body is limited, which is not enough to solve this problem. For this situation, the control strategy of motor is analyzed, and a loss suppression method for PMSM based on harmonic injection algorithm is proposed. By suppressing 5th and 7th time current harmonics with highest component content, the loss of motor driven by the inverter is reduced. The fieldcircuit coupling joint simulation model is used as a calculation tool to verify the effectiveness of algorithm. The results show that the loss of motor is reduced by 24.9% after adding harmonic injection algorithm, and the effect of the proposed method is good, which provides a novel method for the loss suppression of motor.