The invention relates to an integrated Buck-flyback high power factor converter. A high power factor and high efficiency are difficult to achieve simultaneously for the traditional converter topology. One end of an alternating current input power supply of the integrated Buck-flyback high power factor converter is connected with an anode of a diode D1, a cathode of a diode D3 and an anode of a diode D5; the other end of the alternating current input power supply is connected with an anode of a diode D2, a cathode of a diode D4 and an anode of a diode D6; a cathode of the diode D1 is connected with a cathode of the diode D2, a cathode of an output diode Do and a dotted terminal of a transformer secondary winding; a synonym terminal of the transformer secondary winding is connected with a positive terminal of an output capacitor and one end of a load; a negative terminal of the output capacitor is connected with the other end of the load, a drain electrode of a switching tube Q1 and an anode of the output diode Do; and an anode of the diode D3 is connected with an anode of the diode D4, a source electrode of the switching tube Q1 and a source electrode of the switching tube Q2. The integrated Buck-flyback high power factor converter can be controlled to perform not only a Flyback circuit function but also a Buck circuit function, so that the high power factor and the high efficiency are achieved.