In recent years, with the application of new technologies in industrial production, the large-scale use of sensitive power equipment, users have higher requirements for electric power quality. Voltage sag as a serious problem affecting power quality, has attracted more and more attention. After a voltage sag occurs, identifying the source of the voltage sag can better determine the responsibility of power suppliers and consumers for power quality issues, effectively resolve disputes between the two parties, and improve economic benefits. This paper proceeds as follows: it is based on the technology of voltage dip source location. The dual power supply network model is established, and the simulation of voltage dip source location is carried out by MATLAB simulation software, and its applicability and advantages and disadvantages are summarized. Finally, an improvement scheme was proposed to improve the positioning accuracy of the voltage dip source.