A pile foundation tower footing impedance measuring device and method thereof, relate to an overhead transmission line tower footing impedance measuring device and method thereof. The device comprisesan auxiliary electrode, a high accuracy flexible Roche coil current sensor, a tower footing impedance measuring device or the like. The footing impedance of the pile foundation tower is measured by program. The invention has features: simple structure, low cost, easy operation, wide measuring current range, strong antijamming capability, high measuring accuracy and low measuring cost, therefore the invention can be widely used for measuring the overhead transmission line tower footing impedance, especially for measuring the tower footing impedance without down lead, incapable or inconvenientof unfastening the down lead, avoiding unfastening the down lead.