Abstract: To address the corrosion issue of tower grounding down conductors (galvanized steel), a typical galvanic corrosion model of metal down conductor and flexible graphite grounding grid was established. The electrochemical parameters of both flexible graphite and galvanized steel obtained through polarization curve testing served as input parameters for the galvanic corrosion model. Subsequently, numerical simulations were systematically conducted to investigate the influence of environmental factors on the galvanic corrosion behavior of galvanized steel in soils with different conductivities, while attempting to reveal the underlying corrosion mechanisms. The results indicate that under simulated soil medium conditions, the significant potential difference between galvanized steel and flexible graphite leaded to high galvanic corrosion tendency. In the grounding device, corrosion current flowed from galvanized steel (anode) to flexible graphite grid (cathode). At direct anode-cathode contact interfaces, significantly elevated corrosion current densities were observed, resulting in markedly enhanced galvanic corrosion acceleration effects. Increased soil conductivity notably promoted galvanic corrosion, manifesting as elevated maximum corrosion rate of galvanized steel. Due to decreasing oxygen content in soil, the maximum corrosion rate of galvanized steel showed a declining trend within 10 d across different conductivity soils. The findings demonstrate that galvanized steel serving as down conductors in novel flexible graphite grounding devices faces high galvanic corrosion risks, necessitating appropriate protective measures for practical applications.