The invention discloses a power factor correction circuit. The power factor correction circuit comprises a converter and a transformer, wherein the input end of the converter is used as the input end of the power factor correction circuit; the input end of the transformer is connected with the output end of the converter, and the output end of the transformer is used as the output end of the power factor correction circuit; the converter is used for converting input voltage to pre-set voltage and outputting the voltage to the transformer; and the transformer is used for transforming the pre-set voltage to obtain output voltage. The invention further discloses a switching power supply applying the power factor correction circuit and a display device. According to the power factor correction circuit disclosed by the invention, the converter is used for converting the input voltage to the pre-set voltage and the transformer is used for transforming the pre-set voltage, so that a wide voltage input range is realized and is wider than a voltage input range of an existing PFC circuit; and the conversion efficiency is high.