Objective To investigate effectiveness of simplified all-arthroscopic Broström technique in treatment of chronic lateral ankle instability in adolescents. Methods A clinical data of 21 adolescent patients with chronic lateral ankle instability, who met the selection criteria and were admitted between June 2023 and May 2024, was retrospectively analyzed. There were 18 males and 3 females with an average age of 16.0 years (range, 13-18 years). T There were 9 cases of left ankle joint injury and 12 cases of right ankle joint injury. Anterior talofibular ligament (ATFL) injury was diagnosed by arthroscopy in all patients. There were 11 cases of cartilage injury, 5 cases of avulsion fractures, and 6 cases of ankle impingement syndrome. The time from first sprain to operation ranged from 3-60 months (mean, 12 months). The ATFL was repaired and the ankle joint stability was restored by simplified all-arthroscopic Broström technique. Visual Analogue scale (VAS) score, Tegner score, American Orthopaedic Ankle Association (AOFAS) score, Karlsson ankle function scale (KAFS) score, Foot and Ankle Scale (FAOS) score were used to evaluate ankle pain and function. MRI were used to evaluate the ligament healing. Results All patients were followed up 8-15 months (mean, 12.6 months). After operation, 1 patient suffered from superficial peroneal nerve injury, 1 patient developed anterior scar impingement on the ankle, 2 patients had superficial wound infection, and 1 patient suffered from sprain again. The VAS score, Tenger score, AOFAS score, KAFS score, and FAOS score significantly improved when compared with the preoperative scores (P<0.05). MRI examination showed the ligament healing and good tension. Conclusion For adolescent patients with chronic lateral ankle instability, using simplified all-arthroscopic Broström technique to repair ATFL can effectively alleviate ankle pain, improve stability, and achieve good effectiveness.