During collecting and amplifying bio-electrical signals,potential of electrode often causes inperceivable interference and signal distortion, which could lead to misjudge the normal waveform. The main mechanism is as follows :partial blockage of the first stage amplifier,"high frequency wave chopping" interference,interference of the change of scattering capacity and noise from leakage current of electrode leads. The authors proposed a circuit of correcting electrode potential and high frequency pre-filter,...