Abstract: Grid-connected inverters often use grid voltage feedforward control to improve the suppression capability and startup performance of the system. When the grid behaves a weak grid, the direct proportional feedforward control of the grid voltage will weaken the stability margin of the grid-connected inverter control system. Based on the comparative analysis of the open-loop frequency characteristics of no feedforward and direct proportional feedforward control under weak grids, an improved feedforward scheme is proposed with a lag transfer function for frequency selective in the voltage feedforward channel. Thus the system stability margin improves obviously. Finally, the verification is carried out on a set of LCL-type grid-connected inverter experimental platform. The experimental results demonstrate that the adaptability of improved voltage feedforward strategy under weak grid is more stronger.