With the incessant increase of power system capacity and voltage grade, the safety of grounding grid becomes more and more prominent. How better uniform the surface potential distribution of grounding grid; how to ensure the safety of equipment and personal has become one of the most important topics of grounding researchers who has been working hard to resolve the problem. Based on the electromagnetic field(EMF) and circuit combining theoretical, the paper studies the numerical calculation of grounding grid parameters, and make use of genetic algorithm studies optimization design of the grounding grid, under the condition of that the most touch potential of grounding grid is less than IEEE guide provision value to optimize grounding grid design. Due to genetic algorithm aim to operate coding set of the problem variables, thus maintain a good integrity of variable. Calculation shows that the calculation method is feasible and obtain optimal results which is not subject to hierarchical structure of soil.