Our objective is the designing of a functional electrical stimulation (FES) system on event related desynchronization (ERD) and event related synchronization (ERS) signals. When the brain images the left-and right-leg movements, the ERD/ERS signals will appear. By characterization and characteristic classification, the ERD/ERS will be translated into the response control signal for operating the FES system to electrically stimulate the legs of motor disability. The result shows that the experiment is successful in electrically stimulating the legs of motor disability.