Lin J, et al. - A total of 80 normal adults (40 males/40 females) were recruited in a computed tomography-based feasibility study by the experts in order to assess the feasibility of clivus screw and plate placement by transoral approach and examine its relative anatomic parameters. The vertex of lower incisor was assigned as Point A and the vertical intersection from Point A to extracranial clivus was described as Point B. All the cases were classified into three types, above the top portion (Type 1), between the top and bottom portion (Type 2), and below the bottom portion (Type 3) of extracranial clivus. out of 80, 1 belonged to Type 1 with a B Length of 32.12 mm. With a B Length of 8.7 mm, most cases were Type 2, whereas Type 3’s was − 9.7 mm filling for 37.5%. Among the three types, significant statistic variations were discovered in the anterior skull base angle. The distances from Point A to the top was 97.5 and the bottom portion of the clivus was 96.0 and the pharyngeal tubercle was 96.8 mm. The angles between the tangent of the clivus and the lines from Point A to the above three structures were calculated as 75.7°, 92.3°, and 84.0°, respectively. The distances from Point A to the middle point of the anterior margin of C1 anterior tubercle was 79.1, C2 vertebra was 73.4 and C3 vertebra was 61.5 mm. Hence, in most patients, the clivus screw and plate placement could be achieved through an optimal screw angle by the transoral approach. Moreover, in patients with greater anterior skull angle, mandibular splitting would be required.