The invention belongs to the technical field of a superconducting cyclotron, and specifically relates to a sealing structure of a cryostat for the superconducting cyclotron. The cryostat comprises an annular sealing cabin which is used for placing superconducting coils, wherein the annular sealing cabin comprises an inner cylinder body, an outer cylinder body, an upper flange and a lower flange; the cryostat also comprises a suspension system upper supporting cylinder and a suspension system lower supporting cylinder which are placed on the upper flange and the lower flange, and an electrostatic deflecting plate extraction electrode supporting cylinder, a beam extraction system supporting cylinder, a radial beam detection target supporting cylinder and a suspension system transverse supporting cylinder which are arranged on the outer cylinder body; and the sealing structure comprises a sealing structure between the upper flange and the lower flange, and the inner cylinder body and the outer cylinder body. The sealing structure can be detached and overhauled, is stable in the sealing effect, and capable of ensuring that the superconducting coils can be adjusted and positioned in a vacuum environment.