[Objective] To investigate the treatment of delayed nerve injury caused by old atlantoaxial instability with atlantoaxial pedicle screw combined with plate internal fixation system.[Methods] Open reduction and atlantoaxial pedicle screw combined with plate system internal fixation were performed in 21 patients with old atlantoaxial dislocation. Preoperative measurement was made for all patients with pre-atlantoaxial clearance (ADI) ≥5mm, atlantoaxial canal reserve clearance (SAC) ≤ 13mm, and atlantoaxial instability index (II) ≥40%. JOA score was performed before and after surgery.[Results] Except for 4 patients who could not be reduced and fixed in situ, the remaining patients returned to normal after operation in both the pre-atlantodentate space (ADI) and the atlantoaxial spinal reserve space (SAC).Postoperative follow - up showed good atlantoaxial fusion.Postoperative nerve compression and other symptoms in all patients were improved to varying degrees, and the quality of life was significantly improved.. [conclusion] atlanto-axial joint vertebral pedicle screw plate system is the treatment of chronic atlanto-axial vertebral instability causes late-onset neural damage very effective surgical method, the recovery of postoperative patients with upper cervical stability, on the improvement of the symptoms in patients with nerve injury has a lot of help, and effectively curb the neural spinal cord function further damage, greatly improve the life quality of patients.