Objective: The purpose of this study was to investigate the effects of different frequency on muscle function of the thigh in patients with degenerative knee arthritis during the functional electrical stimulation (FES). Method: For this study, 16 male participants over 65 who patients with degenerative knee arthritis were recruited as research participants. In this research, isokinetic muscular function, EMG, and joint position sensation were performed after FES treatment was applied for three conditions (FES 20, FES 50, and Without FES). For each dependent variable, one-way ANOVA with repeated measures was to determine whether there were significant differences among three different conditions (p<.05). When a significant difference was found, post hoc analyses were performed by using the contrast procedure. Results: When compared to FES 50 and without FES, FES 20 causes significant increase in isometric knee extension strength. No significant differences were found in EMG values across different EMS conditions. Conclusion: The present study examined isokinetic muscular function, EMG, and joint position sensation in order to investigate the effects of different frequency muscle function of knee extensors during the functional electrical stimulation. The results of this study showed that FES with 20 Hz frequency had positive effect on knee extensor. Based on the findings of the present study, FES with lower frequency may help the performer to focus on developing strength in knee extensor muscles.