Objective To study the clinical application of Sinew knife in the treatment of the third lumbar transverse process syndrome.Methods 80 patients with the third lumbar transverse process syndrome, who visited the Department of Orthopaedics, Beijing Hospital of Traditional Chinese Medicine Affiliated to the Capital Medical University from March 2016 to February 2017,were selected as the research subject, and divided into two groups by random number table.The control group was treated with small needle knife.The observation group was treated with Sinew knife.The therapeutic effect of the two groups was observed, the JOA scores and VAS scores were compared between the two groups before and after treatment, and the levels of related oxygen free radical metabolism indexes were detected in the two groups.Results The total effective rate of the observation group was 97.50%,which was significantly higher than that of the control group（82.50%）（P<0.05）.After treatment, JOA scores of two groups were increased significantly, VAS scores decreased significantly, the difference was statistically significant（P<0.05）;VAS score of the observation group after treatment was significantly lower than that of the control group, JOA score was significantly higher than that of the control group（P<0.05）.Conclusion The treatment of the third lumbar transverse process syndrome with Sinew knife has definite curative effect.