The invention discloses a single-leaf push-pull type movable threshold protective air-tight door structure and a closing method thereof. The single-leaf push-pull type movable threshold protective air-tight door structure comprises a wall body, a door frame, lock seat mechanisms, a guide rail and a door leaf. A door opening is formed in the wall body, the door frame comprises a door-shaped frame and a movable doorsill, the door-shaped frame is connected to the wall body and located on the two sides and the top of the door opening, the movable doorsill is detachably connected to the bottom of the door opening and hermetically connected with the door frame, and sealing strips are arranged on the periphery of the door frame; the lock seat mechanisms are arranged on the wall body or the door frame and located on the two sides of the door opening; the guide rail is connected to the wall body and extends to the top of the door opening; a hanging wheel is arranged on the door leaf, the hanging wheel is slidably connected to the guide rail, and locking mechanisms are arranged on the two sides of the door leaf; and when the door leaf slides to the door frame along the guide rail, the lock seat mechanisms are matched with the locking mechanism in a limiting mode, so that the door leaf translates towards the door frame to press the closing strips to seal the door opening. A hinge-free translation structure is adopted, a large door leaf opening space is not needed, and the single-leaf push-pull type movable threshold protective air-tight door structure is more suitable for a special building environment with a small door opening space at the hole.