The power supply source short-circuit capacity of electrified railway is increasing day by day, and the return current of the traction power supply system is important. In an area of high soil resistivity, the design of the main grounding grid of a traction substation becomes difficult. This paper proposes that the main indices for measuring the grounding level are contact potential, step potential, ground resistance and ground potential rise. Given a typical soil structure, the main resistance reduction measures such as central grounding grid expansion, extended grounding grid expansion, radial grounding grid expansion and deep well are analyzed and compared. Through a large amount of simulation data analysis of a CDEGS platform, the specific influencing factors of each resistance reduction measure to the ground index are summarized. By comparing the advantages and disadvantages of the measures, the law of resistance reduction of grounding grid is determined. The best scheme is recommended. The simulation parameters in this paper provide the basis for the design of the main grounding grid of the traction substation, and verify the correctness and feasibility of the scheme. This work is supported by Science and Technology R & D Program of China Railway International Co., Ltd. (No. 2017J005-C).