The invention discloses a kitchen ventilator, an impeller assembly for the kitchen ventilator, and a draught fan device. The impeller assembly comprises an impeller, an impeller central disc and a fairing, wherein the impeller central disc is arranged in the wheel cavity of the impeller and comprises a mounting part and a connecting part; the mounting part is suitable for connecting the motor shaft of a motor positioned on one side of the impeller central disc; the connecting part is used for connecting the mounting part and the impeller; the fairing is arranged on the side, back on to the motor, of the impeller central disc and shields the mounting part. The impeller assembly can effectively avoid the abnormal noise and air quantity loss caused by direct impact on the impeller central disc by exhaust gas flows, guides and distributes the exhaust gas flows entering into the middle of the wheel cavity to reduce impact loss to the maximum, and effectively absorbs and reduces noise of frequency bands in the kitchen ventilator to optimize the noise of the entire kitchen ventilator.