Abstract:[Objective] To compare the preliminary clinical outcomes of arthroscopic reconstruction of anterior talofibular ligament (ATFL) versus the traditional open reconstruction for chronic lateral ankle instability (CLAI) . [Methods] A retrospective study was done on a total of 46 patients who underwent ATFL reconstruction for chronic lateral ankle instability in our hospital from February 2015 to March 2020. Among them, 24 patients underwent arthroscopic ATFL reconstruction, while the other 22 patients underwent conventional open AT- FL reconstruction. The perioperative, follow-up and imaging data of the two groups were compared. [Results] All patients in both groups were successfully operated on without serious complications. The arthroscopic group proved significantly superior to the open group in terms of total incision length, intraoperative blood loss and hospital stay (P<0.05) , despite of the fact that no significant differences were noted in operation time and incision healing between them (P>0.05) . The arthroscopic group resumed walking and full weight-bearing ac- tivity significantly earlier than the open group (P<0.05) . Compared with those preoperatively, the anterior drawer test and varus test signifi- cantly improved (P<0.05) , AOFAS scores significantly increased (P<0.05) , the ankle dorsal extension- planter flexion range of motion (ROM) remained unchanged (P>0.05) , and VAS score significantly decreased (P<0.05) at the latest follow up in both groups. The ar- throscopic group was significantly better than the open group in the abovementioned indicators at the last interview (P<0.05) . Radiographi- cally, talus anterior displacement and talus lateral inclination measured on stress X-ray films were significantly reduced in both groups at the last follow-up compared with those preoperatively (P<0.05) , which was not significantly different between the two groups at any corre- sponding time points (P>0.05) . [Conclusion] The arthroscopic ATFL reconstruction achieves better clinical outcome over the conventional open reconstruction for chronic lateral ankle instability.