An electronic device includes a microphone, a bias-supply device and a voice-recognition device. The bias-supply device is configured to provide a first bias voltage to serve as an operation voltage of the microphone, when the electronic device is operated in a power-saving mode, such that the microphone transforms a voice signal into a first output signal. The voice-recognition device is configured to receive the first output signal and output a control signal, when the first output signal has a predetermined signal, to enable the electronic device be operated in a normal operation mode and the bias-supply device to provide a second bias voltage that is higher than the first bias voltage to serve as the operation voltage of the microphone, such that the microphone transforms the voice signal into a second output signal and outputs the second signal to a core circuit.