Abstract: The design of the circuit in this paper is the audio power amplifier,the sound signal from the microphone through the OP07 constitute a two-stage single supply of small signal amplification module amplifier.And then filtered through the RC bandpass filter bandwidth of 200 Hz~10 kHz,filtered signal connected to the power amplifier module to zoom in and sent it to the speaker to play.At the same time,after the signal power amplification connected to the peak detection module for the use of SCM,SCM display howling frequency and howling suppression using double T network through the FFT detection.The circuit also uses the programmable analog switch to realize the output power control.Measured the actual loudspeaker maximum undistorted power is higher than 5W,the overall efficiency of the circuit is 83,whistle suppression module work after the microphone speaker distance of 30 cm or more does not produce howling,which meet the subject requirements indicators.