Abstract: The typical soil medium environment in Henan was simulated, and the galvanic corrosion behavior between the typical "metal downconductor (galvanized steel)-graphite grounding grid" was studied. The results showed that the potential difference between the metal downconductor and the graphite grounding grid reached about 700 mV under the simulated soil medium conditions, which had a significant tendency of galvanic corrosion. Among them, the self-corrosion potential of the downconductor galvanized steel was more negative, and it was the anode of the galvanic corrosion, and the corrosion process would be accelerated; the electrical conductivity and oxygen content had significant effects on the galvanic corrosion behavior between these two materials. With the increase of electrical conductivity and oxygen content, the galvanic current density increased. Compared with the uncoupled samples under the conditions of 15% oxygen content and 1000 μS/cm conductivity, the galvanic corrosion acceleration rate reached 13.36 and 5.18, respectively, and the galvanic acceleration effect was obvious; the increase of the area ratio also had a significant promoting effect on the galvanic corrosion; the galvanic corrosion susceptibility grade between the above two materials reached the highest grade E under the conditions of this study. In the new graphite grounding grid device, the galvanized steel down-conductor had a high risk of galvanic corrosion. In actual use, the combination of the above two materials should be avoided as much as possible. If it was unavoidable, reasonable protective measures should be taken.