Purpose: This study is a case study that analyzes the effects after planning and applying a functional training program to improve the performance of high school male freestyle wrestler. Methods: The subject of this study was one elite athlete in freestyle wrestling at K High School in D Metropolitan City. The contents of the applied functional training program consisted of 5 items related to flexibility, 5 items related to dynamic stabilization, 8 items related to muscular endurance, and 8 items related to muscle power improvement in consideration of the wrestling competition situation. After applying the functional training program twice a week at a frequency of 120 minutes per day for 5 weeks(10 times), changes in body composition, basic physical strength, maximal exercise load test, anaerobic exercise capacity, knee joint isokinetic strength and muscle power were analyzed. Results: Body composition, basic physical fitness, maximal exercise load test, anaerobic exercise capacity, isokinetic muscle strength and muscle power were measured before and after the application of functional training, and most of the measurement items showed positive changes after application of the program. In particular, a positive change in exercise duration and maximal oxygen intake as a result of the graded maximal exercise test indicates an improvement in cardiopulmonary endurance, and a decrease in peak drop among the anaerobic exercise capacity measurement items increases tolerance to fatigue. In addition, positive changes in knee joint isokinetic muscle strength and muscle power are very important physical factors for improving the wrestler s performance, and it is judged that the effect of the functional training program applied in this study is appropriately reflected. Conclusions: In summarizing the results of this study, the planning of the optimal functional training program taking into account the physical characteristics of the sport and individual athletes showed more developmental changes than the previous physical fitness training which depended on the intensity of training and the amount of training. This training method was considered to show the possibility of being fully utilized for the future improvement of elite athletes performance.