Purpose: We investigated how nerve mobilization influence ankle plantar flexor muscles of the affected lower extremity on the spasticity in stroke patients. Method: Total 12 patients were recruited, who had spasticity on ankle of the affected lower extremity, and applied nerve mobilization on the sciatic and tibial nerves in supine position. H-reflex was measured using EMG equipment, detected the ratio of maximum H/M and H-reflex latency, and compared the changes before, during, right after, 5 minutes after and 10 minutes after the application of nerve mobilization. The data were analyzed using repeated measure ANOVA to compare the changes in length of time. Results: In comparison with the ratio before nerve mobilization, the ratio of maximum H/M was significantly decreased during nerve mobilization(p<0.05), and it tended toward recovery right after, 5 minutes after and 10 minutes after applying nerve mobilization, there was no statistically significant difference(p>0.05). In comparison with the ratio before nerve mobilization, the ratio of maximum H/M was most significantly decreased during the first 10 seconds after nerve mobilization and it tended toward recovery gradually(p<0.05). In comparison with the H-reflex latency before nerve mobilization, it was significantly increased during nerve mobilization(p<0.05) and it was decreased right after nerve mobilization, After 5 and 10 minutes, it had a tendency toward recovery but it revealed no statistically significant difference (p>0.05). Conclusion: It is considered that nerve mobilization could contribute to initial rehabilitation with stroke patients for relieving spasticity and nerve contracture.