[Objective] To discuss the mechanism and relative problems of lumbar traction. [Method] Relevant articles and retrospect clinical data in the author's hospital were reviewed. Review relevant articles and retrospect clinical data of our hospital. [ Result ] Traction force : 40 kg + 15% ～ 20% of body weight, fineness rate reached 83.5% in 1606 patients being treated. According to course of disease, fineness rate was 90. 1% in the group of less than 3 years, 68.2% in the group of more than 3 years. [ Conclusion] Lumbosacral nerve root leave the peak of the protruding nucleus and establish a new harmonious "root-disc" relationship after traction. The pressure and tension to the nerve root reduces or disappears, meanwhile, the pain of low back and leg is alleviated or eradicated. Appropriate traction weight and correct traction body posture are key factors of good therapeutic effect.