Abstract: Aiming at the problems that the wide range variation of grid impedance under weak grid reduces the stability of grid-connected inverter system, the grid-connected current waveform distortion caused by grid background harmonics and the positive resonance peak generated by voltage feed-forward self-tuning filter, a control strategy of voltage feed-forward self-tuning filter combined with parallel adaptive virtual impedance of inverter system is proposed. Firstly, a single-phase LCL-type grid-connected inverter model is established, and the influence of grid impedance on the inverter system is analyzed. The phase margin of the inverter system is improved by the voltage feed-forward self-tuning filter. Then, the control strategy of the inverter parallel adaptive virtual impedance is adopted to weaken the positive resonance peak generated by the voltage feed-forward self-tuning filter, further improve the phase margin of the inverter system, ensure that the inverter system has better dynamic and steady-state performance, reduce the influence of the grid background harmonics on the grid-connected current, and improve the adaptability of the inverter system to the weak grid. Finally, a simulation model is established in Matlab/Simulink and a DSP power conversion test platform is built to verify the effectiveness and practicability of the proposed control strategy.