In view of the difficulties brought by the wide application of frequency converters in current engineering practice to the motor design and simulation calculation, the permanent magnet synchronous motor was modeled and simulated by the method of field-road coupling. In this paper, the loss classification and calculation of permanent magnet synchronous motors, the calculation method of temperature rise and its application are summarized. Then, focusing on the principle and coupling relationship of field-road coupling, the advantages compared with other control methods, taking a 1.8 kW surface-mount permanent magnet synchronous motor as a classic and necessary example, finite element simulation, open-loop field-road coupling simulation, and id = 0 double closed-loop vector control field-road coupling simulation are established, and the field-road coupling is more suitable for the actual operation of the motor through the above simulation comparison experiments, and the open-loop control loss is four to six times higher than that of closed-loop control and finite element simulation. Finally, the development trend of this method in the future is summarized and prospected, which can play a reference role for the research of permanent magnet synchronous motors under the premise of different load.