An alternating current (AC) power supply measuring circuit includes a voltage dividing circuit, a measuring integrated circuit (IC), a control board, and a first power rectifying circuit. The voltage dividing circuit receives an AC voltage signal and divides the AC voltage signal to a first voltage dividing signal and a second voltage dividing signal. The measuring IC receives the first and second voltage dividing signals to obtain an AC voltage measuring signal. The control board receives the AC voltage measuring signal and processes the AC voltage measuring signal. The first power rectifying circuit provides a floating ground signal to the voltage dividing circuit.