Abstract: A driving circuit of an AC fan motor has an AC to DC converter, a regulated voltage divider, a motor driving unit, two windings each having many coils and a harmonic wave suppression unit. The AC to DC converter converts AC power to high voltage DC power. Since the motor driving unit requires low voltage DC power, the motor driving unit is connected to the AC to DC converter through the regulated voltage divider. The two windings are directly connected to the AC to DC converter to obtain the high voltage DC power. Therefore, when the motor driving unit drives the windings, a large current will pass through the winding to increase rotation ration. Since each winding has many coils, the large current can be held in a suitable range to prevent the winding from being damaged by the large current.