Objective To study the clinical efficacy of lateral collateral ligament reconstruction surgery combined with arthroscopy in treatment of chronic lateral ankle instability. Methods 60 cases with chronic lateral ankle instability were selected,the patients were divided into the study group and the control group according to a random number table,which has 30 cases in each group.The control group was received conservative treatment,the study group was underwent exploratory arthroscopic ankle cleanup combined with peroneus brevis tendon lateral ligament reconstruction surgery.Scores before and after treatment of the two groups were detected in American bare foot and ankle surgery-hindfoot score system(AOFAS).And excellent rate,the recurrence rate and complication rate between the two groups were compared. Results AOFAS score before treatment of the two groups had no significant difference (P> 0.05),AOFAS score after treatment of two groups were significantly higher,and that of the study group was significantly higher than the control group,the difference was statistically significant(t= 9.837,10.873,8.789,all P< 0.05);Excellent rate of the study group was 96.7%(29/30)significantly higher than the 73.3%(22/30)in the control group,recurrence rate of the study group was 0.0%(0/30),significantly lower than the 13.3%(4/30)in the control group,the complication rate of the study group was 3.3%(1/30),significantly lower than the 20.0%(6/30)in the control group,the difference was statistically significant(χ2= 13.982,15.037,13.298,all P< 0.05). Conclusion Lateral collateral ligament reconstruction surgery combined with arthroscopy in treatment of chronic lateral ankle instability has better clinical efficacy,the recurrence rate is low,and has less complications. Key words: Ankle Joint; Joint Instability; Collateral Ligament,Ankle; Arthroscopy