Through simplifying and limiting the practical metro models,the bilateral power supplying system has been studied by using the resistance network model and a theoretical analytic model of the rail potential distribution in the bilateral power supplying system has been established.Computer simulation of rail potential distribution in different traction current is carried out.The results show that the rail potential is affected by substation pitch,the amount of current taken by locomotive,railway portrait resistor,rail-to-ground transition resistor and other factors,the distribution of rail potential is provided from a macro on the qualitative.This gives theoretical basis on solving high rail potential and how to set the distance of substation.Ultimately it provides a good solution to reduce the stray current corrosion.