The invention belongs to the technical field of bridge engineering, and discloses a flat hinge structure of a swivel with super tonnage. The structure is formed by fixedly splicing a plurality of flat hinge units. Therefore, the transport is convenient, the problem of great processing difficulty for the spherical surface of a spherical hinge structure with the super tonnage is solved, the processing is easy, and the construction of the swivel with the super tonnage can be realized. The every two neighboring flat hinge units are fixedly connected by a tenon structure, and the deformation of the flat hinge units, caused by assembly, can be effectively controlled. The structures and the sizes of the flat hinge units are the same, and the processing difficulty and the production cost are further reduced. The structure is suitable for mass production.