The shielded permanent magnet synchronous motor for vacuum pump is seriously heated, so it is of great significance to accurately predict its temperature at the design stage for the safe and stable operation of the vacuum pump system. In view of the fact that the current two-way coupling calculation method of electromagnetic field-temperature field of motor can only consider the influence of temperature on the physical properties of motor materials, a mutual iterative calculation method of electromagnetic field-temperature field of motor is proposed. This method can not only consider the influence of temperature on the loss of motor and the magnetic properties of permanent magnet, but also consider the influence of temperature on the thermal conductivity and heat dissipation capacity of motor components, so that the prediction of electromagnetic field and temperature field of motor is more in line with the actual situation. Taking a 1.5 kW shielded permanent magnet synchronous motor as the research object, the electromagnetic performance and temperature characteristics of the motor are analyzed by using the proposed method, and the analysis results are compared with the electromagnetic thermal two-way coupling calculation results. In addition, the influence of ambient temperature on the temperature rise of the motor is studied by using the proposed mutual iteration method. This study can not only provide a theoretical basis for the optimal design of the shielded permanent magnet synchronous motor, but also provide a reference for its operational safety and reliability.