Abstract: This paper studies the speed dynamic performance optimization of the interior permanent magnet synchronous motor. In this paper, the current operating point trajectories and the speed dynamic processes under various working conditions are analyzed in detail, and the problems such as current operating point trajectory deviation, speed overshoot and torque fluctuation in the conventional method are revealed. Aiming at these problems, a speed dynamic optimization control strategy based on the variable constraint structure is proposed in this paper. In the proposed control strategy, a variable constraint module is put forward and employed in the speed control loop, and the torque control signal is generated through the speed error, where the control of the speed and torque can be realized synchronously. Moreover, the speed error converges to zero exponentially by using the proposed method, where not only the speed overshoot and torque fluctuation are greatly reduced, but the fluctuation and deviation of the current operating point trajectory are also eliminated. Furthermore, the speed settling time is significantly shortened, and the speed dynamic performance is improved. Finally, experiments are carried out to validate the effectiveness of the proposed control strategy.