Abstract: Clearance-fit (side-fit) spline joints are a key component in a permanent magnet synchronous motor (PMSM) in electric submersible pumping wells. The nonuniform spline clearance affects the output performance of a PMSM. A concept for energy conservation is optimized in this study to improve the modeling accuracy of electromagnetic torque. However, most existing computation models are one-way model with a magneto-mechanical simulation. In this study, a more accurate two-way coupling method is presented for simulating the electromagnetic and mechanical characteristics of PMSM. Additionally, importance should be attached to this two-way magneto-mechanical coupling methodology in an actual simulation. The coupled power, electrical and magnetic energy, and electromagnetic torque equations are solved iteratively until convergence for PMSMs with a segmented rotor and a non-segmented rotor. The optimal electromagnetic torque is obtained for different rotor configurations with the change of temperatures and rotational speeds. The results show that the output performance and electromagnetic torque of the PMSM are seriously affected by the effects of two-way magneto-mechanical coupling and nonuniform spline clearance. The proposed two-way coupling model gives more reasonable predictions than other one-way models do, because the power transfer between the electrical and magnetic energy can be modeled more accurately. The self-centralizing performance of clearance-fit splines and the sensitivity to the radial clearance magnitude lead to the reduction of the electromagnetic torque for the PMSM. Additionally, the electromagnetic torques decrease with the enhanced rotor temperatures and rotational speeds. The best rotor temperature and rotational speed are chosen through a comparison of the experimental results, and then the optimal electromagnetic torque is provided to ensure the output performance of the PMSM in electric submersible pumping wells.