Power factor compensation system and power supply

The invention discloses a power factor compensation system and a power supply. The power factor compensation system comprises a transformer and a phase shift circuit, wherein a primary side of the transformer is connected with a positive end of a voltage-stabilizing and filtering capacitor in a BUCK circuit, and the transformer is used for acquiring an offset voltage of two ends of the voltage-stabilizing and filtering capacitor and transforming the voltage-stabilizing and filtering capacitor to be within an input range of the phase shift circuit; an input end of the phase shift circuit is connected with a secondary side of the transformer, and an output end of the phase shift circuit is connected with a duty ratio control end of a PWM signal of a power supply management chip; the phase shift circuit is used for performing phase compensation on the offset voltage after voltage transformation according to a user instruction, adjusting the voltage after phase compensation to be within aninput range of the duty