[Objective] Canned permanent magnet synchronous motor (CPMSM) is widely used in nuclear power, chemical, and other harsh environments due to the sealing properties of its shielding can. However, eddy current losses in the shielding can lead to significant temperature rise, adversely affecting motor performance. To mitigate these losses and thermal effects while enhancing electromagnetic performance and thermal stability, this paper systematically investigates the electromagnetic-thermal coupling effects of shielding can materials, with a focus on exploring the application potential of non-metallic ceramic materials in canned motors. [Methods] In this study, a CPMSM with rated power of 1.5 kW and a speed of 9 000 r/min was selected as the research object, and a two-dimensional finite element model was constructed, and the shielding can of three materials with different physical properties, were compared and analyzed by using the two-way coupling iterative algorithm of electromagnetic field and temperature field. The effects of physical properties of shielding can materials on the induced electromotive force, air gap magnetic density, loss, torque and efficiency of motors were studied, and their temperature distribution characteristics were deeply analyzed. [Results] The research results demonstrated that when silicon nitride (Si3N4) material was used as the motor shielding sleeve, its insulating properties effectively suppressed eddy current losses, improved motor efficiency and output torque, and increased the fundamental amplitude of the induced electromotive force by more than 11%. Compared to SUS316 and SUS430 materials, Si3N4 ensured more uniform temperature distribution and lower thermal rise in motors. Notably, permanent magnet temperatures were reduced by 30% when using Si3N4 as the shielding material compared to SUS316. [Conclusion] As a new high-performance shielding can material, Si3N4 has excellent characteristics such as electrical insulation, non-magnetism and high thermal conductivity. It can effectively suppress eddy current, optimize electromagnetic characteristics and enhance the thermal stability of motor. It has an important application prospect in the design of efficient, reliable and low loss motor.