Abstract: To improve the tracking and synchronization performance of a multi-motor synchronous system under steady-state disturbances, a synchronous speed controller is designed based on the speed controller in a traditional mean-coupled structure, thereby effectively reducing the complexity of the controller structure. In order to improve the robustness and dynamic performance of the system, particle swarm optimization algorithm and improved variable speed integral term are introduced to optimize the controller parameters. The improved system is referred to as MCC_PSO system. Multi-motor synchronous control system model was built with three permanent magnet synchronous motors (PMSM) in MATLAB/Simulink, and the simulation results show that in terms of tracking performance, the motor speed overshoot is reduced by 10 r·min⁻¹, the adjustment time is shortened by 0.01 s, and the variation of motor speed is reduced by 5 r·min⁻¹ after the load surge. In terms of synchronization performance, the synchronization errors between motors 1 and 2, 1 and 3, and 2 and 3 are reduced by 1.1 r·min⁻¹, 1.2 r·min⁻¹ and 0.4 r·min⁻¹ respectively, after a sudden load increase, which demonstrates that the improved synchronization control system is superior to the traditional control system in terms of tracking performance and synchronization performance.