The invention discloses a Q[8] large-duct supermolecule self-assembly body and synthesizing method thereof, and belongs to the technical field of covalent organic framework polymers. The Q[8] large-duct supermolecule self-assembly body is formed by the induction with transition metal ions. The formation general formula is Q[8].2[MC14].4H3O.aH2O, wherein M represents transition metal ions, and a represents the quantity of crystallized water molecules, and is greater than or equal to 51 and less than or equal to 68. The invention discloses a synthesizing method of the Q[8] large-duct supermolecule self-assembly body. The method has the characteristics that operation is simple and cycle is short.