Abstract: The axial permanent magnet magnetic bearingless flywheel machines(APM-BFM) mostly operate in high power fast charging and discharging state, and its high power density and internal stator topology make it suffer from prominent problems such as high thermal load, complex losses and significant temperature rise. The basic structure and operating principle of the APM-BFM are described, and an accurate temperature field analysis model considering the effect of skin effect on eddy current losses at high frequencies is developed using a modified variable coefficient IEM5 model, and the loss variation pattern of the machine at different speeds is analysed. Based on this, a three-dimensional finite element simulation is used to calculate the steady-state temperature field of the machine, and the temperature property parameters of the electromagnetic material and the machine losses are updated according to the results of the temperature field calculation, so that a more accurate analysis of the maximum temperature rise and temperature distribution of the machine can be obtained through the magnetic-thermal bi-directional coupled finite element method. This will provide a reference for the optimal design and efficient application of heat dissipation in complex operating conditions of APM-BFM.