Objective To set up the three-dimensional finite element model of lumbar in normal people and osteoporotic patients,and to evaluate the effect of the geometry and the materrial properties differentiation caused by osteoporosis on the load distribution and on stress and strain fields evaluated by FEA were examined.Methods One healthy female and one female patient with severe osteoporosis were selected.The data were obtained by means of spiral CT scanning.Three-dimensional model were established by Mimics 10.0 software.Two models were chosen and modified in Hypermesh 10.0 software to generate mesh.Attributes of materials were given to establish model of three dimensional finite element.Import the model into Abaqus6.9 to analyze biomechanical characteristics.Results L5 three dimensional finite element models in normal people and osteoporotic patients were successfully established.In the healthy LS,the maximum value of von mises stress was 4.171 Mpa,the peak value of axial displacement was 1.693e-2 mm,and the peak value of the axial strain was 5.508e-5.In the osteoporotic LS,the maximum value of yon mises stress was 4.451 Mpa,the peak value of axial displacement was 3.822e-2 mm,and the peak value of the axial strain was 1.414e-4.Conclusion The stress was not higher in the osteoporotic L5 than in the healthy one for a normal daily loading situation.Compared to the healthy one,the osteoporotic L5 structure is prone to stress concentration,and not to infrequent "error" loads.