In the design and practical application of highspeed permanent magnet synchronous machine (HSPMSM), there is a multi-parameter, strongly coupled relationship between the machine and the drive. Drive harmonics have a significant impact on machine losses and thus on the overall efficiency. First, a 100kW, 60krpm machine and drive system is modelled accurately to study the strongly coupled electromagnetic field of the motor and drive. The model includes an accurate model of the slot conductor, which facilitates the calculation of AC copper loss. An electromagnetic field-circuit coupling model of the HSPMSM, which enables the study of the high coupling regulation between the machine and the drive. Second, based on the comparison between the ideal sine wave current source and the drive harmonic power supply, the effect of the drive harmonic on various losses of the machine is studied, such as AC copper loss, stator core loss, permanent magnet (PM) and sleeve eddy current loss. The laws and coefficients of the effect of drive harmonics on the various loss of the machine are obtained, which is of great significance for the design and development of HSPMSMs. It provides a useful reference for the design, development and application of HSPMSMs.