An AC electrical power dividing circuit includes a hot line, a neutral line, a ground line, two output ports, a first voltage-dividing module, a second voltage-dividing module, a first sampling resistor, and a second sampling resistor. The hot line is coupled to the ground line via the first voltage-dividing module and the first sampling resistor in turn. The neutral line is coupled to the ground line via the second voltage-dividing module and the second sampling resistor in turn. One of the output ports is connected to a node between the first voltage-dividing module and the first sampling resistor. Another one of the output ports is connected to a node between the second voltage-dividing module and the second sampling resistor. The AC electrical power dividing circuit supplies adjustable AC power to an AC electrical device from a 110 V or a 220V power source.