Abstract: The subway operation causes the transformer DC bias and buried pipeline corrosion, which requires the interference and impact assessment of metro stray current. A modeling method of dynamic earth potential distribution caused by metro stray current is proposed. By using the multiple power supply sections as an equivalent resistance network model with multi-power accumulation, the real-time distribution calculation of stray current is realized. Based on the numerical integration of the point current source electric field and geographical information, the dynamic calculation of the potential during the train turnover time is realized. Using CDEGS software simulation and field measurement data, the accuracy of the proposed model is verified. Taking two metro lines as an example, the potential fluctuation interval is calculated, and the stray current disturbances range is evaluated with potential gradient. The influence of train operating conditions, rail-ground transition resistance and soil resistivity factors on potential gradient is analyzed.