Based on theoretical calculations and engineering practice for the grounding resistance of the vertical grounding electrode using a steel pipe, an analysis is made of the relationship between the effect of the resistance reduction using the deep well method and soil resistivity, as well as the depth and diameter of the ground electrode. Its characteristics include: the deeper the depth, the worse the effect of reduced resistance; the bigger the soil resistivity, the better the effect of resistance reduction; the bigger the diameter, the worse the effect of reduced resistance. The characteristics of the effect of the resistance reduction using the deep well method are explained qualitatively from the influence of the grounding electrode current density and discharge end effect. Simultaneously, considering the earth skin effect of lightning current and the construction cost, it is concluded that the deep well method is not recommended in the areas with lower soil resistivity; after the grounding electrode diameter size reached a certain size, increasing the diameter of the grounding electrode will have little effect in the resistance reduction, so the diameter of the grounding electrode should not be too big.