We first prepared graphene oxide (GO) by an improved Hummers method, and then Ni-loaded TiO2/PEI/RGO nanocomposite catalyst was fabricated with the PEI modified graphene oxide suspension, NiCl2 and Ti(SO4)2 precursor through a hydrothermal method at 180 °C by using PEI as a linker among the components. The prepared samples were characterized by UV-visible absorption spectrum (UV-vis), Fourier transformed infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that Ni-loaded TiO2 nanoparticles were dispersed uniformly on the surface of graphene sheets and had smaller particle size. The nanocomposites were used as catalysts to remove 4-nitrophenol from wastewater with the help of NaBH4. The results indicated that this catalyst exhibited superior catalytic activity toward the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with a high degradation efficiency above 98 % in aqueous solution, and the catalytic activity was still feasible even over ten cycles.