Constructing high-performance materials that combine high separation efficiency, corrosive environments tolerance and self-healing ability are highly attractive for the next generation oil/water separation materials, but it is still a grand challenge. Here, we report a supramolecular hydrogel network of acrylamide and acrylic acid copolymers (P (AM-co-AA)) and chitosan (CS), sequentially cross-linked by amino-functionalized silica (APTES-SiO2) nanoparticles. The as-prepared APTES-SiO2/P (AM-co-AA)/CS composite hydrogels demonstrate outstanding ductility up to 1360% elongation, and good self-healing ability, combined with excellent under-water superoleophobicity with an oil contact angle above 164 degrees. Most importantly, the underwater superoleophobic properties can be well maintained in various extremely harsh environments, such as acid, alkali and salt solution, providing great potential for oil/water separation in these corrosive environments. Indeed, the hydrogel-coated mesh displays oil/water selectivity above 98.7% at higher water flux.