Objective:To evaluate biomechanically and clinically the posterior STB thoracolumbar transpedicular screw-plate system.Methods:The STB screw-plate system was made by titanium alloy(TC4,Ti6Al4V).The three-dimensional motions of T12～L1segment of six adult fresh spine specimens in normal,injured,Steffee fixation or STB fixa-tion states were measured and analyzed.Axial stiffness of STB system was also measured.Clinical results of STB system in the treatment fifty-three cases with thoracolumbar fracture and lumbar spondylolisthesis were ob-served.Results:Both Steffee and STB devices can restore the stability of injured thoracolumbar verte brae in flexion,extension,lateral bending and axial rotation,especially in right/left lateral bending.No statistical differ-ence of spinal stability capacity was found between Steffee and STB devices.The axial stiffness of STB device was106.8N/mm±24.8N/mm.Clinical results showed that STB has excellent reduction and fixation capacity on injured thoracolumbar vertebrae.Conclusion:STB has excellent bromechanical properties and can be used in the thoracolumbar fracture and lumbar spondylolisthesis.