Abstract: A dual-input power switching system includes a first DC power source, a second DC power source, a DC conversion circuit, and a boost-up circuit. The first DC power source provides a first DC voltage, and the second DC power source provides a second DC voltage. The DC conversion circuit receives the first DC voltage or the second DC voltage being an input voltage, and converts the input voltage to supply power to a load. The boost-up circuit provides a hold-up voltage to boost up the input voltage when the first DC power source stops supplying power to lead to power drop of the input voltage, such that the input voltage reaches to a specific voltage that is greater than the second DC voltage and afterward naturally decreases to be less than or equal to the second DC voltage.