Abstract: When using the traditional three-pole method to measure the underground electrode grounding resistance, there will be a large measurement error, which suggests that the method will not be suitable for the underground electrode grounding resistance measurement. In view of this problem, this paper proposes a new method for measuring the electrode grounding resistance by using the geo-electric resistivity observation system, which is so called direct measurement method. And then, the grounding resistances of the underground observation power supply electrodes of Pinggu seismic station in Beijing were measured by using the traditional three-pole method and the direct measurement method. The measurement results show that, compared with the traditional three-pole method, the direct measurement method can get more reliable measurement results with less error, and can save human and material resources and measuring time.