A conjoint foldable covering structure for brewing materials used to accommodate brewing materials at a first state before soak or at a second state after soak and comprising: a foldable body that allows water flows to penetrate, developing hollow space in which a stretching direction is defined and circular cross sections are perpendicular to said stretching direction, and comprising fold line units and openings (12 and 12') at two opposite ends; and a first lid and a second lid, which join both ends of said foldable body and cover said two openings, and the first lid and the second lid coordinate with said foldable body to surround and define an accommodation space; said foldable body having both ends adjustably arriving at a retractive position based on the volume of said brewing materials and based on said fold line units along said stretching direction when said brewing materials are at the first state; and said fold line units along said stretching direction also allows both ends to stop at a brewing position based on said fold line units along said stretching direction when said brewing materials are at the second state so that said foldable body can appropriately stretch in a brewing process with a proper shape wherein said foldable body with both ends joined by said first lid and said second lid is also soaked in water; wherein said first lid comprises a first lid body and a first pull tab: said first lid body has two opposite surfaces which join said foldable body's one side and said first pull tab, respectively; said second lid comprises a second lid body and a second pull tab; said second lid body has two opposite surfaces which join said foldable body's other side and said second pull tab; characterized by the fact that: said conjoint foldable covering structure further comprises food-grade waterproof glue by which said first lid and said second lid adhere to both ends of said foldable body; said foldable body allows both ends to bend inwardly and join said first lid body as well as said second lid body, or said foldable body allows both ends to bend outwardly and join said first lid body as well as said second lid body; said first lid further comprises a first upholder which is situated beyond junctions of said first lid body and said foldable body and said second lid further comprises a second upholder which is situated beyond junctions of said second lid body and said foldable body; said first upholder and said second upholder which are oppositely arranged will arrive at a position wherein said first upholder and said second upholder contact with each other when both ends of said foldable body arrive at the retractive position; and said first upholder and said second upholder are approximately perpendicular to said first lid body and said second lid body, respectively. a foldable body that allows water flows to penetrate, developing hollow space in which a stretching direction is defined and circular cross sections are perpendicular to said stretching direction, and comprising fold line units and openings (12 and 12') at two opposite ends; and a first lid and a second lid, which join both ends of said foldable body and cover said two openings, and the first lid and the second lid coordinate with said foldable body to surround and define an accommodation space; said foldable body having both ends adjustably arriving at a retractive position based on the volume of said brewing materials and based on said fold line units along said stretching direction when said brewing materials are at the first state; and said fold line units along said stretching direction also allows both ends to stop at a brewing position based on said fold line units along said stretching direction when said brewing materials are at the second state so that said foldable body can appropriately stretch in a brewing process with a proper shape wherein said foldable body with both ends joined by said first lid and said second lid is also soaked in water; wherein said first lid comprises a first lid body and a first pull tab: said first lid body has two opposite surfaces which join said foldable body's one side and said first pull tab, respectively; said second lid comprises a second lid body and a second pull tab; said second lid body has two opposite surfaces which join said foldable body's other side and said second pull tab; said conjoint foldable covering structure further comprises food-grade waterproof glue by which said first lid and said second lid adhere to both ends of said foldable body; said foldable body allows both ends to bend inwardly and join said first lid body as well as said second lid body, or said foldable body allows both ends to bend outwardly and join said first lid body as well as said second lid body; said first lid further comprises a first upholder which is situated beyond junctions of said first lid body and said foldable body and said second lid further comprises a second upholder which is situated beyond junctions of said second lid body and said foldable body; said first upholder and said second upholder which are oppositely arranged will arrive at a position wherein said first upholder and said second upholder contact with each other when both ends of said foldable body arrive at the retractive position; and said first upholder and said second upholder are approximately perpendicular to said first lid body and said second lid body, respectively.