[Objective] To evaluate The feasibility and effectiveness of Transforaminal Percutaneous Endoscopic Lumbar Discectomy via Superior Border of Inferior Pedicle Approach for Severe Down-migrated Disc Herniation. [Methods] From February 2016 to March 2020，a total of 27 patients with severe down-migrated disc herniations were treated with transforaminal percutaneous endoscopic lumbar discectomy via superior border of inferior pedicle approach.There were16 males and 11females with an average age of 40.12 years old. The follow-up were from 5 to 38 months.The VAS，ODI and JOA were adopted to evaluate the surgical effectiveness preoperatively and postoperatively. [Resluts] All cases were follows up. Postoperative JOA (15 points method) score was 13.59 which had been significantly improved compared with the pre-operative score 1.37. Postoperative VAS score of pain of lumbar was 1.36 which had been significantly reduced compared with the pre-operative score 6.93. Postoperative VAS score of pain of leg was 1.01，Pre-operative VAS score of pain of leg was 8.31.Postoperative ODI score was 23.23%，Pre-operative ODI score was69.02%.All the postoperative follow-up scores were better than those pre-operative, and the difference was statistically significant(P<0.001)The execellent and good rate was 94.38%. [Conculsion] Transforaminal Percutaneous Endoscopic Lumbar Discectomy via Superior Border of Inferior Pedicle Approach can be feasibile and effective in the treatment of severe down-migrated disc herniations. The operative should have rich experience in spinal endoscopy