[Objective] To explore the efficacy and feasibility of the unilateral biportal endoscopic (UBE) decompression for thoracic os- sification of ligament flavum (TOLF) . [Methods] A retrospective study was performed on 29 patients who receiced surgical decompression for TOLF in our hospital from January 2018 to May 2021. Bases on preoperative doctor-patient communication, 12 patients underwent UBE, while the rmaining 17 patients were treated with the traditional open laminectomy. The documents regarding perioperative period, follow-up and radiographs were compared between the two groups. [Results] All patients in both groups had corresponding surgical procedures per- formed successfully without serious complications. The UBE group proved significantly superior to the open group in terms of total incision length, postoperative walking time and hospital stay (P＜0.05) , regardless of that the former took significantly more intraoperative fluoroscopy than the latter (P＜0.05) . However, there were no significant differences in terms of operation time and incision healing grade. All patinets in both group were followed up for (14.0±1.3) months on a mean, and the patients in the UBE group resumed full weight-bearing activity signifi- cantly earlier than those in the open group (P＜0.05) . The ODI and JOA scores, as well as pyramidal tract sign significantly improved over time in both groups (P＜0.05) , whereas which were not statistically significant between the two groups at any matching time points (P＞0.05) . Radiographically, the thoracic kyphosis angle, the spinal canal area and the sagittal diameter of the spinal canal were significantly increased in both groups after operation (P＜0.05) . Althogh no significant differences in aforesaid imaging data were found between the two groups pre- operatively (P＞0.05) , the UBE group had significantly less thoracic kyphosis angle and posterior bone loss than the open group postopera- tively (P＜0.05) , regardless of no significant differences in spinal canal area and canal sagittal diameter between them postoperatively (P＞ 0.05) . [Conclusion] Both UBE and open decompression are effective treatments for TOLF. By comparison, the UBE takes benefits of reduc- ing iatrogentic trauma with minimal bone structure and stability affected, facilitating postoperative recovery, declining the postoperative tho- racic kyphosis.