Research conclusions: ( 1) It’s necessary to upgrade design method to ensure safety of the grounding grids of special or very important traction substations by using computer － aided design software． ( 2) The maximum short － circuit current should not be taken as the grounding current，the effect of overhead ground wire connected with the grid should be considered，and the current divider coefficient should be calculated． ( 3) The designers should adopt unequally spaced arrangement in optimizing grounding grid when necessary． ( 4) The designers should not hold the opinion that copper must be resistant to corrosion，they also should take the effect of galvanic corrosion and environmental factor of the soil into consideration．