The aim of the work is modeling of the heat flow in an electric motor with permanent magnets with a height of 56mm. Numerical calculations were carried out for a simplified 3D model prepared in the Autodesk Inventor solid modeling program. The bodies were prepared on the basis of the existing model and constructional documentation of the actual engine. In the next step, the simplified solid model was imported into a commercial Autodesk Simulation Multiphysics computing package and into authorial software in which it was supplied with appropriate material properties and discretized. In the next stage, the model was calibrated and verified on the basis of a preheating attempt of the actual object. The motor winding was supplied with direct current and was a heat source with a power of 40 W. In the steady state, temperatures were recorded at selected points. Then, on a discredited numerical model, computer simulations corresponding to the actual heating test were carried out. When comparing the temperature values ​​obtained at the points corresponding to the measurement points, the model was calibrated, which corrected the thermal resistance parameters assumed in the calculation model. Finally, the model (after the implemented changes) was verified with results obtained with commercial and authorial software.