Abstract: The fretting wear behaviors of 304 stainless steels under various loads were investigated using an Optimal SRV-IV oscillating friction and wear tester. The worn surfaces morphologies and compositions were investigated using scanning electron microscopy and energy dispersive spectroscopy. The results indicate that the load and fluid had a pronounced influence on fretting wear behaviors and wear mechanism. Under dry sliding condition, the fretting regimes depended on load, i.e. the fretting regimes gradually transformed from gross slip to partial slip as the load increased to 50 N. The friction coefficient and wear depth decreased with the increase of load. Correspondingly, the wear mechanism transformed from the combination damage of adhesion wear, abrasive wear and oxidation to local fatigue damage and mild oxidation. Compared to dry sliding condition, due to the lubrication of aqueous water, the adhesion of surface was effectively suppressed, the friction coefficient decreased significantly, and the contact surface was prone to slip, the partial slip regime disappeared. The wear depth gradually increased with increasing load under artificial sea water. The synergtic effect of abrasion and corrosion under artificial sea water led to greater damage than that under demonized water. Abrasive wear and mild corrosion wear dominated under artificial sea water.