Objective To investigate the biomechanical influence of vertebroplasty on the adjacent vertebral body and intervertebral disc. Methods Six fresh cadaver specimens were applied to make 6 T 12-L 2 function spine unit (FSU) as group A,and 6 L 3-L 5 FSU as group B, respectively. All the FSU were underwent flexion-axial loading to result in middle vertebral body fracture. Following reduction,the middle fractured vertebral body were strengthened by the method of vertetroplasty, with group A using Calcium Phosphate Cement (CPC), group B using Polymethylmethacrylate(PMMA) respectively. Before fracture and after vertebroplasty, all the FSU were conducted biomechanical test. Results In the CPC group(group A), the stiffness of middle vertebral body were enhanced by 19%, without any affection on the stiffness and strength of the whole FSU, the stiffness of upper vertebral body decreased by 6.7%, the height of upper disc is decreased evidently. In group B, even when the stiffness of middle vertebral body were 5 to 6 times augmented, the stiffness and strength of the whole FSU were still not affected ,the stiffness of upper vertebral body decreased by 24.4%, the height of upper disc were decreased very evidently. Conclusion Following vertebroplasty, the enhanced vertebral body don't result in great stress concentration in the adjacent vertebral body, especially with CPC, it means that vertebroplasty technique is safe in the respect of biomechanics. While some extend of stress concentration are present in the adjacent dise, which will possibly accelerate disc degeneration process.