The invention discloses a dual-purpose hole sealing device for gas extraction and coal seam water injection and a using method thereof. The dual-purpose hole sealing device consists of an extraction tube/water injection tube, a high-elasticity rubber tube, an integrated type elastic bag which is formed by inside and outside sealing elastic bags and a connecting tube thereof, and a grouting tube, wherein the extraction tube/water injection tube passes through the rubber tube, and is in sealing connection to two ends of the rubber tube; the water inlet tube and a water drainage tube are separately equipped with a switch and a one-way valve; the integrated type elastic bag covers the rubber tube; the grouting tube passes through the inside and outside sealing elastic bags which are in sealingconnection to the grouting tube, one-way valves are arranged in the inside and outside sealing elastic bags, and explosion valves are arranged between the inside and outside sealing elastic bags. Theusing method for the dual-purpose hole sealing device comprises the following steps: injecting water, grouting, grouting towards a grouting space through the explosion valves, stopping grouting, re-injecting water before slurry is solidified to keep water pressure constant, and taking out the extraction tube and the rubber tube to repeatedly use after gas extraction or water injection is accomplished. The dual-purpose hole sealing device can completely remove gas in the grouting space, eliminates appearance of drilling cracks and increases a crack sealing range in drilling surrounding rock bykeeping grouting pressure constant, and increases gas extraction amount or improves water injection effect.