Objectives: To evaluate the influence of dynamic pedicle screws on the stability of the Atlantoaxial Joint. Methods: A series of in vitro biomechanical tests were performed using six fresh adult cervical spines (occipital bone-C4 segment) to simulate different conditions in surgery including the (1) intact state; (2) injury state: type II odontoid process fracture; (3) rotating pedicle screw: two rotating pedicle screws were bilaterally inserted in the Atlas pedicle and the Axis was fixed by two ordinary polyaxial pedicle screws, which were connected by a titanium rod with a diameter of 3.5 mm; (4) sliding pedicle screw: two sliding pedicle screws were bilaterally reinserted into the Atlas pedicle with other internal fixation components unchanged in comparison with (3);（5）rigid fixation：Atlas and the Axis were fixed by four ordinary polyaxial pedicle screws, which were connected by a titanium rod with a diameter of 3.5 mm. Biomechanical studies of samples were performed under intact, injury and various fixation statements using a spinal testing machine, while applying a constant moment of 1.5 Nm in flexion-extension, left-right lateral bending, and left-right axial rotation directions. A repeated measurement design was employed in all tests. Movement were measured consecutively by an Optotrak Certus 3D measurement system in order to analyze the range of motion (ROM) and neutral zone (NZ) of Atlantoaxial Joint. Results: In the atlantoaxial joint, ROM in C1 and C2 of the injury state caused by odontoid process fracture was significantly larger than the intact state in flexion, extension, lateral bending and rotation (P<0.05). ROM of fixation segments was significantly reduced in flexion, extension, lateral bending and rotation directions when rotating and sliding pedicle screw fixations were used (P<0.05), compared with the intact state. A significant increase in ROM for rotating and sliding pedicle screw fixations in lateral bending was obtained, compared with rigid fixation (Protating screws=0.024, Psliding screws=0.001). NZs of fixation segments for rigid fixation, rotating pedicle screw fixation, and sliding pedicle screw fixation were significantly reduced (P<0.05). There were no significant differences among these fixations (P>0.05). Conclusions: In the atlantoaxial joint, stability of using two rotating screws or sliding screws for fixation was comparable to rigid fixation in flexion, extension and rotation directions, but was weaker in the lateral bending direction. Dynamic screws fixation can maintain the relative stability of the atlantoaxial joint.