An impedance matching method for an electret microphone is provided. In some embodiments, the impedance matching method includes collecting a bias voltage between a source and a drain of a field effect transistor built in the electret microphone; determining whether the bias voltage is within a preset bias voltage threshold range; and if it is detected that the bias voltage is not within the preset bias voltage threshold range, sending a corresponding control signal to adjust load bias impedance so that the bias voltage is within the preset voltage threshold. An impedance matching apparatus for an electret microphone and a communication device are also provided.