The invention provides an expanded tube leaking stoppage device capable of being assembled and released. The expanded tube leaking stoppage device comprises a drill pipe connecting device, a releasing device and an expanded tubular column, wherein the head and the tail of the drill pipe connecting device are connected with each other in the up-down direction; the drill pipe connecting device is a hollow tube; the expanded tubular column is coaxially provided with an assembling grouting tubular column; the upper end of the assembling grouting tubular column is connected to the expanded tubular column through a grouting tubular column joint; the lower end of the assembling grouting tubular column is mounted on a flexible freight bag fixing base; a flexible freight bag sleeves the assembling grouting tubular column; the upper end and the lower end of the flexible freight bag are fixed through a flexible freight bag coupling and a flexible freight bag fixing base respectively; the lower portion of the flexible freight bag fixing base is connected with a guiding shoe; a plurality of sieve holes are uniformly distributed in the assembling grouting tubular column; and the flexible freight bag is wound on the assembling grouting tubular column via a water-sensitive wire. By the expanded tube leaking stoppage device capable of being assembled and released, injected solidifiable leaking stoppage materials can be solidified in limited space, a karst cave structure is modified, and a supporting body with required height, a certain diameter and certain strength is established on a channel in which a well track penetrates.