The invention relates to a method for dynamically adjusting busbar voltage to improve grid connection efficiency. The working range of grid voltage from lowest limit to highest limit is divided into at least two levels and each level corresponds to a set busbar voltage directive value; and a control system detects the effective value of the grid voltage in real time, and when the grid voltage is within one level, if the busbar voltage directive value at the moment is not equal to the set busbar voltage directive value corresponding to the level, the busbar voltage directive value is adjusted to the set value. Since the amplitude of the busbar voltage is dynamically adjusted according to the grid voltage value detected in real time, the invention has the advantages that the overall efficiency and the reliability of the grid-connected inverter are improved, the device stress is reduced and the service life of the capacitor is prolonged.