Based on the multi-conductor transmission line（MTL） model， the equivalent circuit of traction substation and sectioning post is derived， and a general mathematical model is established. This model is suitable for the analysis of traction power networks fed by different power supply modes. Parameter identification method is used to establish a model of induction motor in parallel with the static part of trains traction and drive system to realize trains exact modeling. On this basis， the simulation software based on coupling between train and network for traction power supply system of electric railway is developed. Calculation results of actual example show that the method fully considers interactive influence of trains and traction power supply system， and possesses good generality and reliability properties.