In this paper, we describe how harmonic voltage in transmission networks influences harmonic currents in distribution networks. In the conventional equivalent circuit for harmonic analysis based on computer simulations, harmonic currents in distribution networks were regarded as a constant harmonic current source. However, results of experiments using distribution system equipment indicate that the harmonic currents vary if individual harmonic distortion (IHD) of the sending voltage in transmission networks or phase angle difference between the fundamental voltage and the harmonic voltage in transmission networks varies. To analyze the results, this paper proposes a new circuit model of the harmonic currents in distribution networks. Computer simulations using EMTP were also carried out and the results were compared with results of experiments for the verification of the proposed circuit.