As for many reported polymer-crosslinked membranes, challenges remain in terms of membrane fouling, complex processing, high cost and poor degradability. Herein, all-natural multiply self-crosslinking cellulose membrane (SC membrane) was fabricated by blending long and short cellulose micro/nanofibers in a simple crosslinker-free manner. The forming of abundant and compact hydrogen bonding among cellulose fibers enables SC membrane with strong network structure, showing excellent mechanical performance without any extra additives. Due to the plentiful hydroxyl groups, SC membrane possesses underwater superoleophobicity and low oil adhesion. As a proof-of-concept, separation of oil-in-water emulsions using the SC membrane was demonstrated, exhibiting fine separation performance, outstanding reusability and anti-fouling performance. Importantly, SC membrane with admirable thermal stability and corrosion resistance, holds great promise in harsh conditions. Therefore, from perspective of environment sustainability and preparation technology, the SC membrane with supreme properties is expected to open up new avenues for the development of functional cellulose-based membranes.