Abstract: High-performance systems expect smooth and steady speed from the motor. However, the speed loop of permanent magnet synchronous motor (PMSM) drives is affected by multi-source disturbances, resulting in aperiodic and periodic fluctuations in the output speed. To suppress the multi-source disturbances in the speed loop, this paper proposes a resonance-improved single-degree-of-freedom active disturbance rejection controller (ADRC). The single- degree-of-freedom ADRC retains the capability of the traditional ADRC to suppress the aperiodic disturbance. Based on this, the quasi-resonant controller is used to expand the bandwidth of the observer of the single-degree-of-freedom ADRC at the specific frequency to further improve the capability of the single-degree-of-freedom ADRC to suppress the periodic disturbance. Therefore, the proposed method can simultaneously suppress the aperiodic and periodic speed fluctuations to improve the speed control performance. In addition, the stability of the proposed method is analyzed using the Nyquist stability criterion. Finally, the effectiveness of the proposed method is verified by experiments.