Embodiments of the invention disclose a method and a system for signal analyzing and a processing module of the system. The signal analyzing system includes a plurality of first electrodes, a plurality of second electrodes, and a processing module. The first electrodes transmit a plurality of first input signals. The second electrodes transmit a plurality of second input signals. The processing module generates a body electrical signal according to at least one of the plurality of first input signals and at least one of the plurality of second input signals, generates a first filtered signal corresponding to the plurality of first input signals, generates a second filtered signal corresponding to the plurality of second input signals, and generates a lead signal according to the body electrical signal, the first filtered signal and the second filtered signal.
