To evaluate the stability of thoraclumbar spine after longitudinal impact with different energy. Methods: The fresh specimens of T12-L2 and L2-L5 were divided into three groups and were impacted with three different energy separately. Three dimensional motion were tested and roentgenograms and CT scan were taken before and after the impact. Results: Motion of superior or inferior lumbar were not changed after lower energy impact; but it increased after medial energy impact; after high energy impact the motion increased significantly(P<0.05). Conclusions: Three dimensional motion test is better than radiodiagnosis to evaluate the stability of thoraclumbar in laboratory.