<p>The grounding materials in high-voltage direct current transmission systems are highly susceptible to corrosion due to electrochemical polarization effects induced by stray direct currents. This corrosion can lead to grounding system degradation and power system failures and ultimately pose significant economic losses and safety hazards. To further reveal the influence mechanism of direct current (DC) density on the corrosion behavior of carbon steel in acidic red soil leaching solution, the effect of DC density on the corrosion behavior of carbon steel in acidic red soil leaching solution was systematically studied by means of surface analysis, weight loss method, and electrochemical measurement. The results showed that the corrosion area ratio of Q235 carbon steel increased significantly from 61.7% at 0&#xa0;A/m² to 87.0% at 200&#xa0;A/m² after 28&#xa0;days with the increase in DC density in the acidic red soil leaching solution, and showed a stronger time-cumulative corrosion effect under high current density. With the increase in current density from 50 to 200&#xa0;A/m², the content of FeOOH corrosion products with stronger conductivity increased by 65.4%. This structural evolution formed a loose and porous corrosion product film, leading to a 36.6% reduction in charge-transfer resistance (<i>R</i>_ct). Furthermore, a mechanistic transition from pitting to crack propagation was observed: The maximum pitting depth reached 41.1&#xa0;μm at 100&#xa0;A/m² (2.1 times that of natural corrosion), while at 200&#xa0;A/m², the average surface roughness increased to 8.85&#xa0;μm. Ultimately, the applied DC imposed severe anodic polarization, serving as a DC-induced anodic polarization that enhanced the dissolution process of iron, and increased the accumulation of Fe³⁺ ions, increasing the overall corrosion rate from 0.31 to 1.74&#xa0;mm/y—a 5.6-fold increase compared to non-current conditions.</p>