Stainless steel (SS) have been widely used in marine structures and food industry due to its high corrosion resistance and excellent mechanical strength. Marine structures such as ships, ocean engineering and offshore rigs, are easily attacked by crude oil generated by oil spills and SS vessels applied in food industry are fouled by the organic matters in the fluid. Here, fish-scale-like SS surfaces with superhydrophilic and underwater super-oleophobic property, including 316 L SS mesh and 304 SS plate, are designed by a facile chemical-based oxidation method. The obtained SS surfaces show excellent underwater anti-crude-oil-fouling property and thermal stability. Furthermore, the obtained 316 L SS mesh can effectively separate crude oil/water mixture solely driven by gravity. Significantly, the as-prepared SS surfaces possess robust antifouling and self-cleaning property during multiple cycles with the aid of Fenton-like catalytic reaction between Fe (III) and H2O2 or calcination at high temperature. Therefore, the fish-scale-like SS surfaces show great potential in a wide range of fields, such as marine antifouling, oil-water separation and food industry.