Due to the increase in oil spill accidents and discharge of oily wastewater, it is urgent to develop functional materials to separate oil from oil/water mixtures. In this work, the kaolin-coated meshes were fabricated by a facile coating method to construct a micro-hierarchical surface and controllable pore size for the separation of various oil/water mixtures. The obtained meshes exhibits super-hydrophilicity, underwater super-oleophobicity with underwater oil contact angle > 150 degrees and outstanding oil/water separation efficiency above 99% and flux up to 190 L m(-2) h(-1) under gravity force. Moreover, the mesh still maintained high stability and good separation efficiency under corrosive condition and recycling. Furthermore, the mesh can also remove water from the water-in-oil emulsion. Results from this study are meaningful for the development of low-cost, and eco-friendly materials with high efficiency and mechanical robustness for oily wastewater treatment and open a new way for high-increment utilization of kaolin mineral.