Abstract: In view of the influence of interference on permanent magnet synchronous motor control system, an improved f_aln function based active disturbance rejection control for permanent magnet synchronous motor was proposed. An active disturbance rejection controller of permanent magnet synchronous motor is designed. By analyzing the influence of f_al function on the active disturbance rejection controller, an improved f_aln function with limiting amplitude is proposed, and then an extended state observer is designed. The experiment results show that the improved f_aln function based on permanent magnet synchronous motor auto-rejection control method has better anti-interference performance than the traditional auto-rejection control.