Electrospun nanofibrous mats own tremendous advantages and potential in membrane separation process due to their high porosity, large pore size and unique interconnected structure. However, most of membranes reported in the literature were based on phase inversion substrate, and there are few researches focused on applying electrospun nanofibrous mats on membrane separation. From this point of view, this review firstly introduces the electrospinning technology and controllable preparation of electrospun nanofibers, and then sums up the state-of-the- art applications, roles and shortcomings of electrospun nanofibrous mats in membrane separation, including microfiltration, ultrafiltration, nanofiltration and forward osmosis. As for forward osmosis, the progress, currently existing problems, improvement methods and future development directions are emphasized particularly, and a novel three-tier thinfilm composite structure is put forward on the basis of dual-layer thin-film composite structure of forward osmosis membranes. It is sincerely expected that this paper can provide some clues and guidance for further research and application of electrospun nanofibers in membrane separation.