Aiming at the problem of low computational accuracy when analyzing the electromagnetic field and temperature field of canned permanent magnet synchronous motor by the directional coupling method, a magneto-thermal bidirectional coupling method is proposed. Firstly, a magneto-thermal coupling computational model is established. Secondly, the influence of the can sleeve material on the motor performance is analyzed by the magneto-thermal bi-directional coupling method, and the calculation results are compared with the directional coupling method. Finally, a three-dimensional model of the motor is established and the electromagnetic field and three-dimensional temperature field are analyzed using finite element software. The results show that the proposed magneto-thermal bi-directional coupling calculation method can effectively improve the calculation accuracy of electromagnetic field and temperature field. In addition, the can sleeve using non-conductive non-magnetic materials can effectively improve the efficiency of the canned permanent magnet synchronous motor and reduce the temperature rise of the motor. The proposed method not only provides a reference for the design of canned permanent magnet synchronous motor, but also is of great significance to ensure the efficient and reliable operation of the motor.