The resonance problem of multi-inverter grid-connected systems in weak grids has been widely discussed. When the background harmonics are taken into account, the grid voltage feed-forward link of the inverter introduces a positive feedback path, which will further deteriorate the power quality of the system. Thus a resonance suppression method for impedance reshaping of multi-grid-connected inverters with background harmonics accounted for in a weak grid is proposed. By dividing the control links of inverters into conductors, a triple-decomposition conductor-based equivalent model of the multi-inverter grid-connected system is established. The resonance characteristics of the system are obtained using the modal analysis method for the variation of the number of inverters and the grid-side impedance. Taking into account the grid voltage feed-forward and capacitor current feedback links, the weighted average current control is improved and impedance remodeling of the inverters is performed by connecting virtual conductors in parallel at the point of common coupling to achieve suppression of the system resonance in a weak grid. Simulation results show that the proposed method can both greatly reduce the influence of background harmonics on the inverter output current and effectively suppress the resonance of the multi-inverter grid-connected system in a weak grid.