At present, most of alternating current intrusion fault detection devices are fixedly installed, while, with such kind of installation mode adopted, a specific fault point cannot be judged and positioned; some mobile grounding fault finding devices take alternating current intrusion faults as common grounding faults and perform troubleshooting through injecting a low-frequency signal. The invention belongs to the electric power detection technical field and provides a portable mobile alternating current intrusion fault detection and positioning device. The portable mobile alternating current intrusion fault detection and positioning device comprises a host signal source and a hand-held detector; the host signal source is used for monitoring whether alternating current intrusion exists in a direct-current system, displaying voltage and alternating current components in the direct-current system and issuing data information to the handheld detector; and the handheld detector performs alternating current intrusion point troubleshooting according to received data information. According to the portable mobile alternating current intrusion fault detection and positioning device of the invention, a non-fixed installation mode is adopted, and therefore, with a portable mobile type installation structure adopted, the portable mobile alternating current intrusion fault detection and positioning device can move to find a fault point and position a specific alternating current intrusion fault point.