This paper proposes a single-phase buck-boost power-factor-correction (PFC) circuit for universal input voltage. This converter is operated in discontinuous conduction mode (DCM) by using simple control scheme to achieve voltage step-up/down with unity power factor and low total harmonic distortion of input current (THDi). The proposed converter is suitable for universal input voltage (85 - 265 V) and wide output power range. Moreover, the steady-state analysis of voltage gain, boundary operation condition, selections of inductors and capacitors are presented. Finally, a laboratory prototype is built to verify the theoretical analysis.