The invention discloses a control method for a boosting-reducing-voltage grid-connected inverter, and belongs to an inverter control method. The boosting-reducing-voltage grid-connected inverter comprises an input power source, a first filter inductance, a second filter inductance, a first switch tube, a second switch tube, a fifth switch tube, a sixth switch tube, a first switch unit, a second switch unit, a filter circuit and a power grid. The control method includes the steps that driving of a third switch tube and driving of the sixth switch tube are same, and driving of a fourth switch tube and driving of the fifth switch tube are same; on a power-network-voltage negative half cycle, the first switch tube is modulated, and the fourth switch tube is normally opened; on a power-network-voltage positive half cycle, the second switch tube is modulated, and the third switch tube is normally opened. According to the boosting-reducing-voltage e grid-connected inverter, the direct-connection problem of a power tube of a bridge arm of a bridge-type inverter is solved, the reliability is improved; all switch tubes do not need to be provided with dead time, and the waveform quality of power-network currents is improved; single-stage boosting-reducing-voltage conversion can be achieved; only two diodes are required; series tubes are small when branches are conducted, and the efficiency is high.