It decrease the pressure of lumbar through traction, reduce the burden around ligament, bring good rest for damaged lumbar fibrous ring. Under traction condition, the intervertebral space is increased, forming negative pressure space which is good for restoration of prominence. Under traction condition, it can ease the oppression and stimulation which are worked on never root by prominence ,reduce the pain effectively. Traction can promote the blood circulation of parenchyma in waist . Relieve the pains caused by lumbar muscle and rheumatism, enhance stamina and channel meridians. Relax lumbar muscle, restore the energy of backbone. It is very effectivefor adjunctive therapy of chronic lumbar strain.