Embodiments of the present disclosure relate to substance detection technology, and to signal extraction circuits and methods for ion mobility tubes, and ion mobility detectors, which can solve the problem with the conventional technologies that it is difficult to design and manufacture the leadout circuit for the pulsed voltage on the Faraday plates. A signal extraction circuit for an ion mobility tube includes an DC-blocking module configured to remove a DC voltage contained in a voltage extracted, by a signal leadin terminal, from the Faraday plate, and to output, by a signal leadout terminal, a pulsed voltage contained in the voltage extracted from the Faraday plate. An ion mobility detector includes the signal extraction circuit for an ion mobility tube according to the present invention. A signal extraction method for an ion mobility tube includes extracting a voltage on a Faraday plate in the ion mobility tube, removing a DC voltage contained in the voltage extracted from the Faraday plate, and outputting a pulsed voltage contained in the voltage extracted from the Faraday plate. The present invention is used to extract a pulsed voltage from the Faraday plate.