Novel NiO nanowires/nanofibers (NWNFs) hierarchical structures were fabricated employing bottom-up strategy and electrospinning method. The synthesized hierarchical structures were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and nitrogen adsorption-desorption analysis methods. The catalytic efficiency of the NiO nanomaterials developed was evaluated by the photocatalytic degradation of methyleneblue(MB). In comparison with sphere-like and fiber-like structures, the photocatalytic removal rate of MB remains above 97% on the hierarchical NiO NWNFs catalyst under ultraviolet light irradiation for 180 min, which is 1.24 times and 2.16 times that of pure NiO fibers and nanoparticals, respectively. The NiO hierarchical structures show an excellent ability to degrade rapidly a MB pollutant, which may be attributed to its unique hierarchical and porous surface structures.