In order to improve the grid-connected stability of wind power converter, the harmonic and resonance problems of the grid-connected interface of the converter are solved when the load fluctuates. This paper presents an improved active damping linear active disturbance rejection control (ADLADRC) strategy. Firstly, the mathematical model of LCL converter is derived. Traditional active disturbance rejection control technology is analyzed. On this basis, to improve the observation ability of traditional observer, an improved active disturbance rejection control based on series filter in the total disturbance channel of the observer is designed. And the introduction of active damping and its combination to complete the improved ADLADRC control strategy design. Then the frequency characteristics of the converter system under the improved ADLADRC are analyzed by frequency domain analysis method. The improved ADLADRC control has better grid-connection stability and harmonic resonance suppression. Finally, through simulation, the proposed control strategy is compared with the current waveform of traditional LADRC and traditional PI control. Under the steady-state condition, the simulation results show that the full-load harmonic rate of the improved ADLADRC is 2.89% lower than that of PI to 0.39%, and the half-load harmonic rate is 7.64% lower than that of PI to 0.60%. It indicates that the proposed control strategy not only has better grid-connected stability, but also has fast dynamic response and harmonic suppression when the load fluctuates.