Objective: The magnetic expansion control (MAGEC) system, developed by NuVasive, has demonstrated positive surgical outcomes in treating early-onset scoliosis. However, clinical studies have indicated that the MAGEC system is challenged by insufficient tensile force, which can lead to failed elongation surgeries. The maximum torque of the rotor inside the growth rod significantly affects the tensile force of the growth rod. The larger the maximum torque of the rotor, the greater the tensile force of the growth rod. Because of the different body weights of patients, the relative positioning of the rotor and driver in the clinical application of the MAGEC system is also different. Therefore, the distribution space in which the rotor can rotate continuously has a significant impact on clinical treatment. To solve the problem of insufficient tensile force, it is necessary to optimize the maximum torque of the rotor and to maximize the distribution space for continuous rotation of the rotor. Methods: This study employs ANSYS Maxwell to establish a finite element simulation model for a circular distributed drive permanent magnet rotor system. The analysis investigates the effects of the angle between the drive permanent magnet and the rotor, pole pairs, rotor outer diameter, and drive permanent magnet speed on the maximum torque of the rotor, and determines the continuous rotation domain of the optimized rotor. To verify the simulation results, a rotor torque measurement device was built and connected to a coupling through a motor. Furthermore, a growth rod extension experiment was conducted to test the magnetron-drive performance. Finally, a growth rod tensile-force testing platform was constructed to test the maximum tensile force of the growth rod. Results: The experimental results demonstrate that optimal performance was achieved when the angle between the driving permanent magnet and rotor was set to 120°, a single pole pairs configuration and an 8-mm outer diameter of the rotor. This combination produces the maximum torque of the rotor and the most extensive continuous rotation distribution space. However, the speed of the driving permanent magnet did not affect the maximum rotor torque. The maximum torque of the rotor before optimization was 32.847 N·mm; The maximum torque of the optimized rotor was 98.970 N·mm, which was 201% higher than that before optimization, and the distribution space for continuous rotation of the rotor was larger. The experiment demonstrated that the maximum torque values of the rotor before and after optimization were 30 and 90 N·mm, respectively, with relative errors of 8.7% and 9.06%, and that the permanent magnets could rotate stably. The maximum tensile force of the growth rod could reach 413 N, nearly twice the maximum tensile force of 208 N of the MAGEC system growth rod. Conclusions: When the angle between the driving permanent magnet and the rotor was set to 120°, the θ values that caused the maximum torque of the rotor to change from large to small were 120°, 140°, 100°, 160°, 80°, 180°, 60°, and 40°. The larger the number of pole pairs, the more rapidly the maximum rotor torque decreases. In addition, the larger the outer diameter of the rotor, the greater the maximum torque of the rotor. Finally, the rotational speed did not affect the maximum rotor torque.