The utility model provides a harmless optical cable fault device of seeking, relates to optical cable maintenance assistant equipment field, including optical cable, communication piece, fixed slot, fixed block, connecting hole, electric wire, wire and power pack, is equipped with the communication piece on the optical cable, is equipped with fixed slot and connecting hole on the communication piece, is equipped with the fixed block in the fixed slot, is equipped with the electric wire in the connecting hole, is equipped with power pack and wire in the communication piece, and the power pack is connected through the wire with the electric wire, the utility model discloses the practicality is strong, uses and installs all fairly simplely, and not only can be fast accurate measuring goes outthe optical cable and takes place fault location, can save the optical cable in addition and detect required equipment cost and human cost, the very big maintenance repair work that has made things convenient for the staff.