Abstract: The electrochemical method and surface analysis technique were used to study the galvanic corrosion behavior of 6061 aluminum alloy (T6 state)-X21A low-alloy steel coupled samples (with different anode cathode area ratios) in simulated seawater. The results show that the self corrosion potential of 6061 (aluminaum alloy) was about -0.73 V, and the self corrosion potential of X21A (low-alloy steel) was about -0.52 V. When 6061 was coupled with X21A steel and became the anode, its corrosion potential shifted positively, the corrosion rate increased, and the galvanic effect significantly accelerated the anodic process. At the same time, X21A steel acted as the cathode, the corrosion potential shifted negatively, and the corrosion rate decreased. As the soaking time prolonged, the electric potential of the galvanic couple sample first remained stable and then gradually shifted negative, the electric current density decreased, and reacheed a relatively stable state. As the ratio of anode to cathode area increased, the electric potential shifted negatively, the electric current density increased, the electric corrosion effect was enhanced, and the corrosion rate increased. This study provides a fundamental theoretical basis for the selection, design, and suppression of galvanic corrosion in ship materials.