To obtain the stray current accurately

a simulation modeling method of long line stray current is proposed based on the CDEGS software. In the model

the longitudinal parallel metal structures in the DC metro line are equivalent to a longitudinal conductor

thus the number of the longitudinal conductors and the number of calculation nodes can effectively be reduced

and the adaptability of longitudinal conductors to sectional spacing and the accuracy of simulation calculation can be improved on the premise of meeting the accuracy required by the project. Under the condition of the same line length and conductor segment spacing

compared with the four-layer stray current model

it is found that the similarity of the simulation results is more than 0.99

the number of segmented nodes is reduced by about 75% and the calculation time is shortened by 98%

which verifies the effectiveness and advantages of the model. Finally

the stray current simulation model of a certain DC metro line in Shenzhen is established

and the effects of train conditions and the deterioration of local insulation performance on stray current are analyzed.