Abstract: The intercity train forms a grounding return channel through the body wheel set rail. Excessive grounding return will cause problems, such as electric corrosion of bearings and abnormal wear of carbon brushes, which seriously threatens the safe operation of the intercity train. The dynamic process simulation model of grounding return current of intercity train running in the power supply section is established in Matlab/Simulink. Combined with the field test data, the accuracy of the model is verified, and the change trend of grounding current of intercity train running in the power supply section is proved. Based on the thermal effect of grounding current, the concept of “equivalent value” of grounding current of intercity train is proposed. The influence of ground return is explored in terms of both working and protective grounding methods. According to the equivalent value of grounding current, the optimization scheme of intercity train grounding system is proposed. The simulation results show that after optimization, the equivalent value of protective grounding current is reduced from 53 A to 17 A, with a decrease range of 67%, the distribution of grounding return current is relatively uniform, and the vehicle body potential is also controlled within a safe range, which provides a theoretical basis for designing a better grounding scheme.