The ground resistance, the ground potential rise, touches and step voltages are the basic design quantities of the grounding grids. Such quantities greatly depend on the safety of grounding system. The aim being pursued is to minimize these mentioned quantities, while the safety restrictions required by the standard regulations are met. The innovative aspect of the proposed approach is the influences of reflective coefficient of two-layer soil and the thickness of upper-layer soil, the irregular grounding grid area are analyzed when using this approach for optimum grounding grid design. By discussing the genetic algorithm, architecture of multi-objective optimization design of substation grounding grids, optimal population size and terminal condition, the realization of the proposed strategy is expounded in this paper. Calculation shows that the method is feasible and the optimal results can minimize these mentioned quantities which are not subject to hierarchical structure of soil and irregular grounding area.