Active de-noising circuit and method of active de-noising earphone

The invention discloses an active de-noising circuit and method of an active de-noising earphone. The active de-noising circuit comprises a microphone, a filter, a first power amplifier, a second power amplifier, and a horn. The microphone is electrically connected with the input end of the first power amplifier through the filter. The output end of the first power amplifier is connected with one end of the horn. A normally-played audio signal is input into the input end of the second power amplifier. The output end of the second power amplifier is connected with the other end of the horn. Noise and normally-played music are independent and separate and are processed by corresponding power amplifiers respectively. Thus, the frequency response and the amplification times of a music signal and the frequency response and the amplification times of a de-noising signal are freely adjusted respectively. Balanced and matching circuits are not required so that the active de-noising circuit is easy to design and produce.