The invention relates to a class-D audio-frequency power amplifier with a carrier wave adjustable module and a carrier wave modulation method thereof, belonging to the technical field of class-D audio-frequency power amplifiers. The class-D audio-frequency power amplifier comprises a prepositive amplification module and a comparator. The class-D audio-frequency power amplifier is characterized byalso comprising a carrier wave adjustable module, wherein the carrier wave adjustable module receives audio signals output by the prepositive amplification module and outputs carrier wave signals of different frequencies according to the input audio signals of different frequencies; carrier waves are input to a second end of the amplifier, and the carrier wave signals are compared with currently input audio signals of a first end of the amplifier; and then the amplifier outputs a pulse width modulation waveform. The class-D audio-frequency power amplifier has good property under the conditions of both high audio frequency and low audio frequency.