A high-voltage power supply module includes a front-end power converting circuit, a first back-end circuit, a second back-end circuit, a ground terminal and a controlling unit. The front-end power converting circuit receives an input voltage and converts the input voltage into a bus voltage. The first back-end circuit receives the bus voltage and outputs a first voltage. The second back-end circuit receives the bus voltage and outputs a second voltage. The first back-end circuit and the second back-end circuit are connected with a connecting terminal. The ground terminal is connected with the connecting terminal. In response to the first voltage and the second voltage, a first control signal and a second control signal are respectively issued from the controlling unit to the first back-end circuit and the second back-end circuit, thereby adjusting the magnitudes of the first voltage and the second voltage.