Control method and device for I-type three-level circuit are disclosed, which can realize zero-voltage turn on of switching tube of high-frequency bridge arm, reduce circuit loss and improve circuit efficiency. The control method includes: detecting a current of an inductor connected with each of high-frequency arm bridges in operation state in the circuit; in a positive half cycle of AC connection terminal voltage of the circuit, when a freewheeling switching tube of the high-frequency arm bridge connected with the inductor is in ON state and a main switching tube is in OFF state, controlling the freewheeling switching tube to keep in ON state and the main switching tube to keep in OFF state if the current does not reach a preset negative current, and controlling the freewheeling switching tube to be turned off and the main switching tube to be turned on if the current reaches the preset negative current.