The experiment was carried out with 8 normal male adult fresh cadaver lumbar spine specimens being used as functional units.The compressive,shear and torsional stiffness of the lumbar disc were measurfed.The results of measurement showed that the compressive stiffness was 1314N/mm.the shear stiffness 242.5N/mm,the torsional stiffness 6.5Nm/deg.The strength of the lumbar disc was 80.3N.Our experimental results showed that the stiffness and strength of the disc was decreased after the posterior vertebral structures or the nucleus pulposus was removed, after the posterior vertebral structures was removed,of which the torsional stiffness was reduced by 51 percent,the torsional strength was reduced by 44 percent.