Abstract: With the advantages of low loss, low cost, high efficiency and high reliability, DC distribution network has become the new trend of the future grid development. There are some power quality problems distinct from AC system in DC distribution network. Through modeling and simulations, the impact on bus voltage power quality of low-voltage DC distribution network is studied under different fault occurred in DC and AC side. Research suggests that fault in DC and AC side will cause voltage fluctuations, voltage sags and harmonics of DC bus, and the difference of the impact on DC bus power quality is obvious with different fault locations, fault impedance and fault types.