The present disclosure illustrates a button detecting circuit and method thereof. The button detecting circuit includes a determining circuit, a voltage selector and a button module. The voltage selector is electrically connected to the determining circuit. The voltage selector has a plurality of candidate voltages arranged in sequence based on magnitudes of the candidate voltages. The button module which is electrically connected to the determining circuit via a single one pin comprises a threshold unit and a button network. The determining circuit receives the candidate voltage outputted from the voltage selector and outputs the candidate voltage to the button module for testing whether the threshold unit will be conducted to find a threshold voltage. The button module generates a scanning current based upon the threshold voltage. The determining circuit senses the scanning current and determines which one of a plurality of buttons disposed in the button network is pressed.