Aiming at the problem that the traditional servo - trajectory planning methods for permanent - magnet synchronous motors (PMSMs) fail to fully utilize the fast performance of the motors under the constraints of rated design, a time - optimal trajectory planning method under the constraints of the short - time overload dynamic feasible region is proposed. Firstly, based on the relationship between the motor"s loss power and motion parameters such as speed and acceleration, the trajectory equation that minimizes the motor"s loss during the servo process is derived using the Pontryagin"s maximum principle. Then, by combining the loss power (current) and bus voltage constraints, the dynamic feasible domain of the servo motor system is reconstructed, and a method for solving the coefficients of the time-optimal trajectory equation that adapts to different angular paths is proposed. Finally, an experimental platform for the servo motor system is set up, and the servo response speeds under the trapezoidal curve trajectory with field-weakening control and the proposed strategy are compared. The experimental results show that the trajectory planning method proposed in this paper outperforms traditional trajectory planning methods in terms of servo response speed under different angular path conditions, saving 6.7% to 9.05% of the positioning time.