According to the spinal anatomy data, three-dimensional geometric model of human lumbar spine L3-L5 segment is established in this paper. In the model, the vertebra is divided into cortical bone, cancellous bone, endplate and other structures. The connection between the vertebrae and intervertebral disc is simulated as contact joint. The material properties of lumbar parts of the structure are not the same, the elastic modulus is changing in the analysis. Based on the model, the deformation of the lumbar spine under different size of axial force and lateral torque is simulated. The simulation result shows the variation regularity of the deformation of vertebrae and intervertebral disc under the condition of different pressure. This research provides a quantitative reference for spinal bio-mechanics. The human spine model with a gradient change sets the foundation for processing field of artificial joint using the 3D printing technology.
