When the soil environment around the grid is determined, optimal desgin of grounding grid is equalize the potential , so as to reduce the touch voltage and step voltage, and as far as possible to save materials, reduce the cost of construction. In order to get the optimal layout scheme of rectangular grounding grid under the condition of non uniform soil, based on the simulation models of square grounding grid built by CDEGS. Frist, get the optimal desgin of grounding grid by change each equalizing belts, and obtained optimization function. The change of the optimization function in different soil reflection coefficient, soil thickness and the area of the grounding grid is studied, and the effect of the rectangular grounding grid is analyzed. The research shows that the design of the grounding grid is related to the soil environment, but also with the rectangular shape. Compare with other methods, this method can reduce maximum touch voltage about 12%..This method can be applied to uniform and non-uniform soil, which can optimize the rectangular and square grounding grids, and optimize effect is according with the basic standards of the power industry.