Under a reasonable predigesting of spinal column, Based on anatomy and biologic mechanics, thispaper proposes a mechanical model about the stability of spinal column keeping perpendicularity.Thereafter, we discuss the function and expression of subsystems of spinal column in detail. By anexample of computing simulation, the rationality of model is indicated. And then, combining themodel and a large number of cases, we analyze the reason that induces the difficulty of restorationin the case that the Centrum is extruded, and the problem that exists in traditional therapeutics. Inthe end, we reveal that it is necessary to make the spasmodic muscle recovered in order to make theCentrum restored.