Objective To study biomechanical effects of the lumbar spine under different traction conditions by using three-dimensional (3D) finite element method. Methods The CT images of lumbar segment L1-5 were input to the Mimics 10.01 for developing 3D geometrical model of L1-5. Then the mesh model of L1-5 was obtained using Geomagic Studio 12.0 and Hypermesh 11.0. The finite element simulation of the lumbar spine under different traction conditions was made by using Abaqus. Results Head-down titling angle was related to the nucleus pulposus stress. When the head-down tilting angle was smaller than 10°, the nucleus pulposus stress regularly changed with the swing cycle; while the head-down tilting angle exceeded 10°, the stress was decreased. In the swing mode, the annulus inner ring stress was increased to promote intervertebral retraction. Conclusions The traction mode helps to relieve the lumbar pain with the swing helping to coordinate the traction effect in each direction, which can better sort out and relieve the rear facet joint disorders. In addition, patients should be careful to select the appropriate traction force in the treatment to achieve good therapeutic effect.