The present invention provides a microphone amplifier circuit, comprising a first transistor, a second transistor, a third transistor, a fourth transistor, a first reference current source and a second reference current source, wherein the gate electrode of the first transistor is used as an input of the microphone amplifier circuit, the source electrode thereof is used as an output, and the drain electrode of the first transistor is grounded through the first reference current source; the gate electrode of the second transistor is connected to the drain electrode of the first transistor, the source electrode thereof is grounded, and the drain electrode thereof is connected to a reference voltage by the second reference current source; the gate electrode of the third transistor is connected to the drain electrode of the second transistor, the source electrode thereof is connected to the source electrode of the first transistor, and the drain electrode thereof is connected to the source electrode of the fourth transistor; and the gate electrode of the fourth transistor is connected to the reference voltage, and the drain electrode thereof is connected to a power supply voltage. Compared with the related art, the microphone amplifier circuit of the present invention has the advantages of low current consumption and high PSRR.