In order to gather information on the lower extremity muscle activity and gait pattern of children with spastic-diplegia cerebral palsy, an electromyographic and kinematic analysis was performed. Three children with diplegic cerebral palsy were selected for the experiment. VICOM 370 kinematic data collection system and Ariel EMG system were used for the study. Kinematic data comparison was made with previous study of 10 children without disabilities using three-dimensional motion analysis technique. Left-right kinematic data comparison was also made. Muscle activities of tibialis anterior, gastrocnemius, rectus femoris and medial hamstring for both legs were measured for comparison among children with cerebral palsy. The following conclusions were drawn from the kienematic data analysis and lower extremity muscle activity comparison. 1) Children with spastic-diplegia cerebral palsy revealed an asymmetrical left-right stance and swing phase in the gait pattern. 2) CSDCP showed shorter single support to keep the stability during walking. 3) Knee flexion for CSDCP during stance phase occurred much earlier than that of normal group. 4) CSDCP hardly dorsiflexed their ankle joint through the gait cycle. 5) Joint movement of CCSDCP was quite different from right to left under similar low extremity muscle activity pattern.