The present invention relates to the technical field of gas production of gas wells, and especially relates to a gas well under-pressure induced-flow plug-removal draining technique. The technique comprises an under-pressure swabbing drainage construction procedure which comprises equipment installation. The equipment installation comprises site layout, vehicle arrangement and derrick erection; and connection of wellhead blowout preventers on the ground, an adapter flange, a hydraulic-drive single-ram blowout preventer, a hydraulic-drive three-ram blowout preventer, a pressure release tee joint and a blowout preventing pipe being connected in turn, the hydraulic-drive single-ram blowout preventer and the hydraulic-drive three-ram blowout preventer forming a blowout preventer group, and the hydraulic-drive three-ram blowout preventer being composed of a shear ram preventer, a blind ram preventer and a semi-sealed ram preventer. The swabbing draining technology and the under-pressure operation technology are organically combined, long-range control and operation of wellhead pressure during under-pressure swabbing operation is realized, operating risks are lowered, the technique is safe and reliable, requirements for gas well under-pressure swabbing draining construction operation are met, and technical blanks in national gas well under-pressure swabbing induced-flow plug-removal draining techniques are filled.