The hemiplegic gait is characterized by the slow speed, the short step length and the increased energy consumption, due to drop the foot and to drag toes. In this study, we developed an active ankle-foot orthosis(AAFO) which could control dorsiflexion/plantarflexion of the ankle joint to prevent dropping the foot and dragging toes during walking for the hemiplegic patient. Then we compared three different gait conditions, gait without AFO(NAFO gait), gait with the conventional hinged AFO without controlling ankle joint(HAFO gait), and gait with the developed AFO(AAFO gait) to analyze kinematics and temporal-spatial parameters of the walking with an active ankle foot orthosis. Results showed that AAFO could prevent not only foot drop by the proper plantarflexion during loading response but also toe drag by the sufficient amount of plantarflexion in pre-swing and reasonable dorsiflexion during swing phase. All temporal gait parameters of the affected side were also improved when the subject walked with AAFO compared to HAFO. The present results indicated that the developed AAFO could have more clinical benefits to treat foot drop and toe drag in hemiplegic patients compared to conventional AFOs.