A touch detection method includes outputting a first signal via an output terminal of a processing unit; receiving a second signal via an input terminal of the processing unit where a voltage level of the second signal corresponds to a voltage level of the first signal, a first capacitance of a first capacitor and a second capacitance of a second capacitor; performing a calibration calculation to the variation of voltage level of the second signal by using a calibration parameter for obtaining a calibrated variation; and determining a touch event has been triggered if the calibrated variation has passed a threshold.