In order to investigate the influence of distributed photovoltaic power generation on the harmonic characteristics of power distribution networks,a simplified model for the theoretical analysis of power distribution network is established，which considers the influences of cable capacitance and reactive power compensation device on the system response characteristics.Next,an actual distribution network model based on Digsilent is constructed by using the constant-current source model commonly used in engineering practice as the harmonic source model,and the model is then used to reveal the harmonic characteristics affected by the PV access mode and the system response characteristics of capacitance.Simulated results show that specific grid structure may amplify the harmonic and cause excessive waveform distortion，and that the distortion level can be decreased by optimizing the access location and dispersion of PV and by improving the filtering channels.