[Objective] Reducing cogging torque is a key issue in motor design. It is widely recognized that slotting the stator teeth of permanent magnet synchronous motor (PMSM) can effectively suppress cogging torque. However, the feasibility of using this method for canned permanent magnet synchronous motor (CPMSM) remains unclear. [Methods] This study investigated a 6-pole, 9-slot CPMSM. A motor model was developed using the finite element method, and stator tooth slotting was implemented. Based on the derivation of the cogging torque expression for the CPMSM, the influence of auxiliary stator tooth slots on cogging torque was analyzed. In addition, the effects of slot number, slot shape, slot position, slot opening width, and slot depth on cogging torque reduction were studied, along with a performance comparison before and after slotting. [Results] The research results showed that, compared with conventional PMSM, the presence of a shielding sleeve in CPMSM reduced the effectiveness of auxiliary slotting for cogging torque suppression. Furthermore, identified as two rectangular slots with a width of w=2.6 mm, a depth of h=0.4 mm, and an offset angle of ??=12.8°, which achieved the best suppression performance on the CPMSM's cogging torque. [Conclusion] The proposed method of slotting the stator teeth of CPMSM to suppress cogging torque is feasible. Additionally, auxiliary slotting reduces the amplitude of air gap flux density and shielding sleeve losses, thereby improving motor efficiency. This study provides valuable insights for the optimization and design of CPMSM.