In recent years, numerous studies have been reported for oil/water separation, such as superoleophilic materials for oil absorption and underwater superoleophobic membranes for continuous separation. However, for the recovery of oil slick pollution on near-shore ocean surface caused by various reasons, large area and fast availability of used materials are needed to be considered. Herein, we report an efficient and environmentally friendly method to fast process nylon mesh by surface diffuse atmospheric plasma (SDAP) for large-area oil/water separation. Nylon mesh is funcionalized by atmospheric plasma to generate micro/nano composite structures on the surface, resulting in superhydrophilicity and underwater superoleophobicity within only seconds. The pre-wetted modified nylon mesh can achieve high efficiency (> 99.9%) and circulating water flux (~ 30,000 L·m⁻²·h⁻¹), with high intrusion pressure (~ 3 kPa) and universality in oil/water separation. Regular plasma unconditionally generated in the atmosphere with the merit of efficiently functionalizing surface has the potential of large-area materials treatment. This study might take one step further for large-area industrial oily wastewater recovery and even oil slicks collection in near-shore water bodies.