A fastening system configured to fasten at least one tank intended to contain liquid hydrogen, the tank or tanks having a center of gravity, the fastening system being intended to be integrated into a fuselage body of an aircraft, the fastening system having a vertical plane of symmetry, the fastening system being linked to an orthogonal frame of reference defined by an axis X intended to be parallel to a longitudinal axis of the fuselage body, a horizontal axis Y and a vertical axis Z, wherein it comprises: - a longitudinal box extending parallel to the axis X, the longitudinal box having a longitudinal vertical median plane that is coincident with the vertical plane of symmetry of the fastening system, the longitudinal box having a horizontal median plane intended to comprise the center of gravity of the tank or tanks, the longitudinal box comprising at least two longitudinal plates (5, 6) that are parallel to the vertical plane of symmetry, - an upper structure fastened to an upper side of the longitudinal box, - a lower structure fastened to a lower side of the longitudinal box, - at least two fastening frames distributed along the axis X, each of the at least two fastening frames comprising symmetrically, on either side of the vertical plane of symmetry, two first fastening devices that are configured to connect a tank to the upper structure by means of a sliding pivot connection of pivot axis parallel to the axis X, the pivot axis being configured to be comprised in a plane perpendicular to the axis Z comprising the center of gravity of the tank; the fastening system further comprising symmetrically, on either side of the vertical plane of symmetry: - at least two second symmetrical fastening devices that are configured to connect a first fastening point of the tank to the longitudinal box, the first fastening point being configured to be comprised in the horizontal median plane of the longitudinal box, - at least two third symmetrical fastening devices that are configured to connect a second fastening point of the tank to the lower structure. - a longitudinal box extending parallel to the axis X, the longitudinal box having a longitudinal vertical median plane that is coincident with the vertical plane of symmetry of the fastening system, the longitudinal box having a horizontal median plane intended to comprise the center of gravity of the tank or tanks, the longitudinal box comprising at least two longitudinal plates (5, 6) that are parallel to the vertical plane of symmetry, - an upper structure fastened to an upper side of the longitudinal box, - a lower structure fastened to a lower side of the longitudinal box, - at least two fastening frames distributed along the axis X, each of the at least two fastening frames comprising symmetrically, on either side of the vertical plane of symmetry, two first fastening devices that are configured to connect a tank to the upper structure by means of a sliding pivot connection of pivot axis parallel to the axis X, the pivot axis being configured to be comprised in a plane perpendicular to the axis Z comprising the center of gravity of the tank; - at least two second symmetrical fastening devices that are configured to connect a first fastening point of the tank to the longitudinal box, the first fastening point being configured to be comprised in the horizontal median plane of the longitudinal box, - at least two third symmetrical fastening devices that are configured to connect a second fastening point of the tank to the lower structure.