Novel hierarchically structured membrane consisting of graphene oxide coating aminated polyacrylonitrile (GO/APAN) fibers were successfully fabricated by controlled assembly of GO sheets on the surface of electrospun APAN fibers and the gap between fibers. This membrane which was superhydrophilic and low-oil-adhesion exhibited ultra-high flux (similar to 10,000 LMH), preferable rejection ratio (>= 98%) and remarkable antifouling performance for the separation of oil-water emulsion. The ultra-high flux was attributed to the large porosity of GO/APAN membrane, whereas the preferable rejection ratio and remarkable antifouling performance were attributed to the smaller GO sheets modified on the APAN fibers and larger GO sheets connected to two or more APAN fibers. More importantly, GO/APAN membrane also exhibited supernormal stability in treating oil-water emulsion with a broad pH range or high-concentration salt, which indicated that the membrane was promising for practical using in oily wastewater. The novel hierarchical structures of GO/APAN membrane greatly enhanced its oil-water separation performance and opened an avenue for designing new nanostructured membrane materials. (C) 2016 Elsevier B.V. All rights reserved.