The configurations of a single-phase dual buck-boost/buck power factor correction (PFC) circuit and a controlling method thereof are provided in the present invention. The proposed circuit includes a single-phase three-level buck-boost PFC circuit receiving an input voltage and having a first output terminal, a neutral-point and a second output terminal for outputting a first and a second output voltages, a single-phase three-level buck PFC circuit receiving the input voltage and coupled to the first output terminal, the neutral-point and the second output terminal, a first output capacitor coupled to the first output terminal and the neutral-point, a second output capacitor coupled to the neutral-point and the second output terminal, and a neutral line coupled to the neutral-point.