A novel hierarchical heterostructures based on alpha-Fe2O3/NiO nanosheet-covered fibers were synthesized using a simple two-step process named the electrospinning and hydrothermal techniques. A high density of alpha-Fe2O3 nanosheets were uniformly and epitaxially deposited on a NiO nanofibers. The crystallinity, morphological structure and surface composition of nanostructured based on alpha-Fe2O3/NiO composites were investigated by XRD, SEM, TEM, EDX, XPS and BET analysis. The extremely branched alpha-Fe2O3/NiO nanosheet-covered fibers delivered an extremely porous atmosphere with huge specific surface area essential for superior gas sensors. Different nanostructured based on alpha-Fe2O3/NiO composites were also explored by adjusting the volume ratio of the precursors. The as-prepared samples based on alpha-Fe2O3/NiO nanocomposite sensors display apparently enhanced sensing characteristics, including higher sensing response, quick response with recovery speed and better selectivity towards acetone gas at lower operating temperature as compared to bare NiO nanofibers. The sensing response of S-2 based alpha-Fe2O3/NiO nanosheet- covered fibers were 18.24 to 100 ppm acetone gas at 169 degrees C, which was about 6.9 times higher than that of bare NiO nanofibers. The upgraded gas sensing performance of composites based on alpha-Fe2O3/NiO nanosheet-covered fibers might be ascribed to the exclusive morphologies with large surface area, p-n heterojunctions and the synergetic performance of alpha-Fe2O3 and NiO.