Abstract: To give a more accurate description of traveling wave,this paper carried out in-depth research on the propagation of traveling waves in overhead lines of distribution power systems,with considering the unbalanced three-phase line,line frequency transmission characteristics and line length.The research shows that the method used for decoupling balanced lines is also suitable for unbalanced lines.The zero-modal traveling wave presents obvious attenuation and dispersion.However,in a relative short distribution line,the attenuation of zero-modal traveling wave is mainly in the high frequency bands.The resolution of zero-modal traveling wave is obviously higher than line-modal traveling wave with considering the power frequency current.This research focuses on the unique features of distribution power systems,and is significant for the future study of traveling-wave based fault detection methods in distribution power systems.