Purpose The purpose of this study was to compare movement of head, trunk and pelvis and to anlysis of correlation with COG during walking between normal and spastic diplegia children. Method Ten children with spastic diplegia who could walk independently and 10 normally developing children were enrolled. Gait analysis were accompanied all of participants. We assessed the statistical relationship among the data of joints, such as the head, trunk and pelvis using Qualisys motion analysis. Result The findings of this study were as follows: First, there was no significant difference on all movements of head-chest between normal and spastic diplegis, but there were significant differences on ML(mediolateral) & vertical movements of head-pelvis and mediolateral movements of chest-pelvis. Second, we did find the correlation between AP(anteriolateral) movements of head-chest and head-pelvis, between AP movements of head-pelvis and ML movements of head-pelvis & chest-pelvis, between ML movements of head-pelvis and ML movements of chest-pelvis & vertical movements of head-pelvis, and between vertical movements of head-chest & head-pelvis. Third, we did find the positive correlations between vertical change of COG and ML movement of head-chest, and between vertical change of COG and vertical movements of head-pelvis during walking. Conclusion This study showed that ML & vertical movements of head-pelvis and ML movements of chest-pelvis in spastic diplegia children were more increased than normal children; therefore, head stability is an important role for increasing gait pattern in spastic diplegia.