A power supply circuit, a compensation circuit and a harmonic distortion compensation method thereof are disclosed. The power supply circuit includes a rectifier and filter module, a main power stage module, a voltage waveform detection module and a compensation module. The rectifier and filter module converts an AC voltage into a DC voltage. The main power stage module receives the DC voltage and provides power to a load. The voltage waveform detection module is configured to detect a waveform of the DC voltage and derive, from the waveform, information about each cycle of the DC voltage. The compensation module is configured to generate a compensation signal based on the information about each cycle of the DC voltage and trigger the main power stage module to perform compensation operation based on the compensation signal. The compensation operation is performed to accomplish total harmonic distortion compensation of the power supply circuit.