The invention discloses an artificial dam construction device of a coal gob area, and a construction method thereof. The artificial dam construction device of the coal gob area comprises a fixed base of which the upper part and the lower part are separately provided with a liquid inlet pipe and a liquid discharge pipe which are connected to the side of the fixed base in a run-through manner; a first baffle abutting against and fixed to the side of the fixed base; a second baffle arranged oppositely to the first baffle and located on the same side of the fixed base; a driving mechanism connected to the second baffle and used for driving the second baffle to approach to or move away from the first baffle; and the liquid inlet pipe and the liquid discharge pipe penetrate through the first baffle and the second baffle in sequence, and the second baffle is provided with a feed opening. According to the artificial dam construction device of the coal gob area and the construction method thereof, the problems of poor airtight performance of an existing artificial dam, poor seepage prevention effect, low construction speed, potential safety hazards and so forth are solved.