A filter mesh was prepared by a facile biomimetic mineralization method with excellent superhydrophilic and underwater superoleophobic properties for the gravity-driven oil-water separations. It shows extremely high permeation flux (>440 kL.m(-2).h(-1)), excellent cycling ability, and high separation efficiency with a chemical oxygen demand (COD) of the filtrate lower than 9 mg/L in several typical oil-water separation processes. The filter mesh also exhibits significant long-term stability of underwater superoleophobic property in the neutral and strong alkaline chemical environment. For instance, it exhibited stable surface oil contact angles (>160 degrees) and high separation efficiency (COD < 7 mg/L) after separating the kerosene-water mixtures with a pH of 7-13. In addition, the liquid wetting models were established to understand the function mechanism of superhydrophilic and underwater superoleophobic surfaces on the oil-water separation.