High performance Al2O3@NFs/PET/NFs separator possessing hierarchically three-dimensional tortuous structure has been developed to promote the cell performance of NFs/PET/NFs separator. The separator comprises a poly (ethylene terephthalate) (PET) nonwoven sandwiched between two poly (vinyl alcohol-co-ethylene) (PVA-co-PE) nanofirous membrane and inorganic Al2O3 coating layers on both sides for surface modification. The Al2O3@NFs/PET/NFs separator shows high porosity and impressively superior electrolyte affinity, thus resulting in higher ion conductivity, smaller interfacial resistance, excellent rate capabilities and cycling performance, compared to the NFs/PET/NFs separator and a commercial PP/PE/PP separator. This high cell performance can be ascribed to synergetic effects of inherent good hydrophilicity of γ-Al2O3 nanopowder coatings and well-designed tortuous nanoporous structure of NFs/PET/NFs membrane. This study suggests that the Al2O3@NFs/PET/NFs separator is a desirable alternative to commercial lithium-ion battery separators, especially promising for large-sized lithium batteries.