Effective treatment of oily wastewater, which is toxic and harmful and causes serious environmental pollution and health risks, has become an important research field. Membrane separation technology has emerged as a key area of investigation in oil–water separation research due to its high separation efficiency, low costs, and user-friendly operation. This review aims to report on the advances in the research of various types of separation membranes around emulsion permeance, separation efficiency, antifouling efficiency, and stimulus responsiveness. Meanwhile, the challenges encountered in oil–water separation membranes are examined, and potential research avenues are identified.