The invention discloses a phase-locked loop bandwidth adaptive grid-connected inverter control method based on the state feedback. In the case of a weak grid, the stability margin of a grid-connectedinverter is degraded or even unstable, low-frequency resonance of the grid-connected inverter is realized by state feedback control based on differential negative feedback while the harmonic amplitudein a low-frequency band of the grid-connected inverter is detected by the discrete Fourier algorithm to adaptively adjust phase-locked loop bandwidth of the grid-connected inverter, the phase marginof the grid-connected inverter under the weak grid is further guaranteed, and grid adaptability of the grid-connected inverter is improved.