The invention discloses a large-current closed inflatable spark interval so as to achieve high reliability, high gas tightness and the like of a gas switch and enlarge application range of the gas switch. The spark interval comprises a metal cover board, an upper electrode supporting base, a lower electrode supporting base, an upper electrode, a lower electrode, an insulating sleeve, an upper metal disc, a lower metal disc, an upper metal hoop and a lower metal hoop, wherein the metal cover board is arranged coaxially. The insulating sleeve is designed through wavy skirt edges so as to increase the edge surface distance between the metal cover board and the lower electrode supporting base. The upper electrode supporting base and the metal cover board are manufactured separately, and the mechanical connection of the upper electrode supporting base and the metal cover board can be achieved through an upper screw. The two metal discs which can move freely are led in so as to achieve the mechanical connection among the metal cover board, the lower electrode supporting base and the insulating sleeve. The upper screw is in tight connection with the upper electrode through a thread structure, a lower screw is in tight connection with the lower electrode through a thread structure, so that replacement is more convenient. A circular truncated cone is designed to ensure the contact area and tightness between each electrode and each electrode supporting base, increase the reliability of the gas switch, reduce the ablation volume of contact portions, and prolong the service life of the switch.