Objective To explore the dynamic characteristics of the thoracolumbar osteoporotic vertebral bodies under free state. Methods Based on CT data from the thoracic and lumbar vertebral body of a healthy female volunteer, model materialization and intervertebral disc tissue reconstruction were realized by using the computerized processing software. The finite element models of normal thoracolumbar vertebral body and thoracolumbar osteoporotic vertebral body were established in ABAQUS 6.14 to perform modal analysis. Results Compared with the normal model, the osteoporosis model had a lower natural frequency and a lager amplitude. As the vibration frequency increased, the model vibration type changed from uniaxial and unidirectional motion to multiaxial and multidirectional motion, and the responsible vertebral body for the maximum amplitude moved down gradually. Conclusions Modal analysis can better analyze dynamic characteristics of the thoracolumbar osteoporotic vertebral body. Patients with osteoporosis should try to avoid the specific vibration environment, so as to decrease the risk of intervertebral disc tissue degeneration, strain of thoracolumbar soft tissues and lesion in posterior structures of the vertebral body.