Oil-polluted water mixtures are difficult to be well separated and thus it is considered as global challenge. A superior superhydrophilic and low-adhesive underwater superoleophobic styrene-acrylate copolymer filtration membrane is constructed using a salt (NaOH)-induced phase-inversion approach. The as-fabricated filtration membrane provides a hierarchical-structured surface morphology, three-dimensional high density open-rough porous geometry with a special chemical composition including high accessible hydrophilic -COO- agents, which all are of great important for long-term usage of immiscible/emulsified (light) oil-polluted wastewater separation. The separation is performed with a high efficiency and a high flux under eighter a gravity-driven force or a small applied pressure of 0.1 bar. The filtration membrane indicates an excellent anti-fouling property and is easily recycled during multiple cycles. The outstanding performance of the filtration membrane in separating oil-polluted water mixtures, and the cost-effective synthetic approach as well as commercially scaled up initial materials all highlight its potential for practical applications.