Objective To evaluate the accuracy and reliability of O-arm-based thoracolumbar pedicle screw installation.Methods A retrospective review was conducted on 75 patients who had undergone thoracolumbar pedicle screw fixation assisted with O-arm navigation (navigation group,n =32) and C-arm fluoroscopy (fluoroscopy group,n =43) from March to October 2014.All the patients were assessed with X-ray and CT images after operation.Accuracy of screw installation in both groups was compared.In navigation group,screw directions were measured on the sagittal and axial images of intraoperative navigation and post-operative CT scanning to evaluate the concordance.Results In fluoroscopy group,a total of 206 pedicle screws were placed with the one-time success rate of 93.2％ and accuracy of 90.8％ for screw placement,and one misplaced screw (grade llⅢ) led to L3 nerve root symptom.In navigation group,a total of 226 pedicle screws were placed with the one-time success rate of 100％ and accuracy of 96.9％ for screw placement,and no screw was grade Ⅲ.Further,there were no significant differences in screw directions on the sagittal and axial images between intraoperative navigation and postoperative CT scanning (P ＞ 0.05).Conclusion O-arm navigation that provides high-resolution images and high precision improves the accuracy of thoracolumbar pedicle screw installation,and possesses good reliability.