This paper presents a magneto-thermal analysis of an external-rotor permanent magnet synchronous machine based on finite element method. The model developed can be used to predict the temperature distribution inside the motor during the rated operation. Electromagnetic computation is carried out with the aid of two twodimensional finite-element simulations of the cross-section of the permanent magnet motor [1]. In addition, the magnetic core losses of the stator and rotor are modelled based on the results from the electromagnetic analysis and a post-processing formula based on the loss-separation principle. To analyse the process of heat transfer in an electrical machine, empirical correlations are used to describe the convective heat transfer from the different surfaces of the permanent magnet motor. The heat transfer coefficients are determined using dimensionless numbers and the Nusselt number [2]. After the loss calculation, the temperatures of the machine are calculated using a three-dimensional finite element method. The results obtained from the model are compared with the experimental results from testing the prototype electric motor.