A screw-rod fixing device specially used for a posterior atlantoaxial vertebrae comprises a pulling screw (2), a supporting point screw (1), variable cross-section fixation rods (3), a lock nut (4), and a screw tail cross-linkage part (5). The variable cross-section fixation rods (3) are connected to the supporting point screw (1) and the pulling screw (2). The screw tail cross-linkage part (5) is connected to two variable cross-section fixation rods (3). The supporting point screw (1) comprises a first tail portion (11) and a first head portion (12). The pulling screw (2) comprises a second tail portion (21) and a second head portion (22). A screw groove is formed in each of the first tail portion (11) and the second tail portion (21), and a U-shaped groove structure is formed in a side surface. Inner threads are arranged in each screw groove. The lock nut (4) is connected into the corresponding screw groove, the variable cross-section fixation rod (3) penetrates through the U-shaped groove structure and is fixed by means of the lock nut (4). The bottom of the screw groove of the supporting point screw (1) is higher than the bottom of the screw groove of the pulling screw (2) by 2 mm to 6 mm. The fixation rod using the above structure improves the safety of a surgical operation and is easy to operate, and a height of 2 mm to 6 mm is increased by bolstering the bottom of the screw groove, thereby improving the pulling reset capability of the screw-rod system.La présente invention concerne un dispositif de fixation à vis-tige spécialement utilisé pour les vertèbres atlanto-axiales postérieures qui comprend une vis de traction (2), une vis de point de support (1), des tiges de fixation à section transversale variable (3), un écrou de blocage (4), et une partie de liaison transversale de queue de vis (5). Les tiges de fixation à section transversale variable (3) sont raccordées à la vis de point de support (1) et la vis de traction (2). La partie de liaison transversal
