In this paper, a simulation model of a distributed photovoltaic grid-connected generation system and a detailed distribution network was built firstly based on Matlab-Simulink, then on this basis, from the standpoint of the voltage deviation and the harmonic contents of the node voltage and the load current, the influence of the grid-connected position and the grid-connected capacity of the distributed photovoltaic grid-connected generation system on the distribution network power quality was quantitatively analyzed. The simulation results show that the closer the grid-connected position gets to the end of the line or the larger the grid-connected capacity is, the greater the influence of the photovoltaic system on the power quality of the distribution network is, and the closer the node gets to the grid-connected position, the more serious the influence is.