In this paper, a thermal analysis method of electric motor based on the magnetic equivalent circuit method and the ensemble thermal network method is proposed, which is convenient for modelling, fast for calculation, and is able to obtain the accurate temperature distribution of the motor quickly. Firstly, on the basis of the proposed unitary magnetic circuit model, all kinds of losses of the electric motor are analyzed and calculated. Subsequently, a thermal network model is established, and multilayered modelling is carried out on the rotor and the stator part in order to obtain more accurate calculation results. In the thermal network solution, the two cases of temperature affecting only the copper resistance and temperature affecting the working performance of permanent magnets at the same time are considered, respectively, and the calculation results in the two cases are compared with the finite element temperature field calculation results, which verifies the validity of the calculation method proposed in this paper.