Abstract: Objective: To study the changes of interior lumbar vertebrae comparing different lumbar manipulations applied by biomechanics Methods: 7 cadaver lumbar spines were loaded on a on a Material Test System,and applied by a computer quantitative control to simulate three manipulations Results: The pressure of lumbar nucleus pulposus for rotation manipulation and sitting rotation manipulation were apparently increased,and the pressure of lumbar nucleus pulposus for traction rotation manipulation were deduced or slightly increased;there were displacements between the nerve roots and lumbar disc;The stress of lumbar facet were lower than the limitation of lumbar facet fracture Conclusion: The mechanism of manipulation may be the relative displacement between the nerve roots and lumbar disc The pressure of lumbar nucleus pulposus were increased,we should pay attention to the scurity