[Objective] Canned permanent magnet synchronous motor (CPMSM) demonstrates excellent performance, including high efficiency and high power density. Due to its compact size, lightweight design, stable and reliable operation, and low maintenance requirements, it is widely used in precision-controlled industrial equipment such as vacuum pumps. During the vacuum pumping process, air may flow into the vacuum environment, causing the vacuum pump to operate under high load conditions and leading to CPMSM overload. [Methods] This study established a co-simulation model using Simulink and Ansys to analyze the electromagnetic and thermal fields of the motor, determining the safe operation duration and the variations in the electromagnetic field under overload conditions. Taking a 1.5 kW CPMSM as an example, different overload torque multiples were set to simulate impact loads. The one-way coupling method was used to calculate the temperature rise in the winding insulation and permanent magnets under overload conditions. [Results] The results showed that the winding insulation of the CPMSM reached its temperature limit after 516 s under 1.8 times the rated load. Continued operation beyond this limit would cause motor damage, while the permanent magnets could still function safely under this load. Therefore, the motor's safe operating time under overload was 516 s. In addition, the study revealed that after overload, regions with higher stator yoke magnetic flux density increased compared to rated load conditions, while the fundamental amplitude of the air gap flux density decreased, and the fundamental amplitude of the back electromotive force increased. After overload, motor's losses increased, while both efficiency and power factor decreased. Additionally, the torque fluctuations first decreased and then increased. [Conclusion] By establishing a simulation model, this paper provides an in-depth analysis of CPMSM's operating characteristics under overload conditions, providing a scientific basis for accurately determining the safe response time after temperature rise. The study summarizes the variations in electromagnetic performance after overloading, which is crucial for improving CPMSM performance.