To analyze harmonic distribution characteristics of distribution network with DG, first, based on the topology between DG and distribution network coupling system, harmonic coupling admittance matrix is deduced, which indicates the changes of impedance network parameter can affect the harmonic distribution; second, a distribution network mathematical model with DG is given, and the factors that influence variation rule of distribution network harmonic voltage distortion rate are analyzed theoretically; finally, a joint simulation system of DG and distribution network is built based on PSCAD, and according to different output and different positions of DG (wind power, solar power), the impact of DG on distribution network harmonic distribution is analyzed. Simulation results show that the positions distribution of DG and different output will influence harmonic distribution directly, which has an important reference value for the locating and sizing of DG.