A noise-reduced capacitive sensing unit is disclosed. The noise-reduced capacitive sensing unit includes: a sensing plate; a first bias voltage source for providing a first bias voltage; a second bias voltage source for providing a second bias voltage; a switch unit, connected between two bias voltage sources and the sensing plate, for selectively providing one of the bias voltages to the sensing plate; an excitation signal source for providing a bi-level waveform; a reference capacitor, formed between the excitation signal source and the sensing plate, for injecting the excitation signal to the sensing plate; and a voltage follower for providing sensing results, wherein an input node of the voltage follower is connected to the sensing plate.