A filtering system, adapted to remove a direct current (DC) component and a high frequency noise component of a touch-sensed signal is provided. The filtering system includes: an analog to digital converter for transforming the touch-sensed signal into a discrete-time input signal; a direct current removing unit for removing direct current components of the discrete-time input signal to obtain a differentiated signal; a de-noise unit for removing noise components of the differentiated signal to obtain a de-noise signal; and a reconstructive unit for processing the de-noise signal to obtain an output signal.