[Objective] To explore the surgical treatment of chronic lateral ankle instability caused by os subfibulare. [Methods] A tatal of 13 patients with chronic lateral ankle instability caused by symptomatic os subfibulare underwent os subfibulare resection, and Brostr?m-Gould procedure with Internal Brace to strengthen the repair of anterior talofibular ligament from May 2019 to November 2020.The patients included 6 males and 7 females, aged 25～50 years with a mean of (36.45 ± 10.20) years. The VAS score and AOFAS score were used to evaluate the postoperative function of the ankle. [Results] All the patients had operation performed smoothly, without serious complications, and got incisions healed well. The followed up period lasted for12～24 months with a mean of (16.35±5.40) months. Compared with those preoperative, the VAS and AOFAS scores significantly improved at the latest follow-up and no complications such as nerve, blood vessel and tendon injury occurred. [Conclusion] For the chronic lateral ankle instability caused by symptomatic os subfibulare which was caused by the destruction of fibrous or cartilaginous connection between os subfibulare and lateral malleolus.os subfibulare resection,Brostr?m-Gould procedure with Internal Brace artificial ligament to strengthen the repair of anterior talofibular ligament does effectively reduce the symptoms,and get early rehabilitation,with definite effect.