Objective　To avoid ICA injury in TARP surgery by studying anatomic  structural relationships between atlas and carotid artery from three-dimensional CTA reconstruction.　Methods　A series of 145 cases underwent TARP surgery were retrospectively selected from January 2012 to June 2015, in whom had performed CTA in neck before surgery. The images were reconstructed by multi-planar reconstruction techniques. The cases with the medial border of the ICA located outside the medial edge of transverse foramen in the atlas transverse center line level were divided into lateral group and the medial group. The parameters were measured including distance from the medial edge of the ICA to perpendicular lines drawn in the axial plane, distance from the medial border of the foramen transversarium to perpendicular lines, deviation distance of the medial edge of the ICA postoperatively. Statistical analysis was carried out to determine if there was a significant difference between lateral and medial by comparing both sides of each segment. The location of the ICA was categorized into 4 areas of C1 lateral mass.    Results    In the medial group，the differences of bilateral d, ipsilateral d and l, D and d were significant（P<0.05）. The offset distance of ICA postoperative was 3.12 mm (F), 3.83 mm (M). The difference was statistically significant compared with the preoperative value.    Conclusions    It is necessary that every patient performs the three-dimensional CTA preoperative to determine the anatomical structures between ICA and C1 lateral mass, then avoid ICA injury and improve the safety of the surgery. Strict periosteal stripping should be taken in surgical exposure process, and the left side in particular should to be more careful.