Halloysite nanotubes (HNTs) were modified by a simple surface covalent functionalization with 3-aminopropyltriethoxysilane (APTES). A novel poly(vinylidene fluoride) (PVDF) ultrafiltration membrane was then prepared by incorporating different ratios of APTES-HNTs. The Fourier-transform infrared (FT-IR), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM) results demonstrated that the HNTs were successfully modified by the introduction of APTES. The morphologies of the membranes were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). In tests of membrane performance, the APTES-HNT/PVDF membrane exhibited a higher pure-water flux (PWF) and a lower contact angle (CA) than a pure PVDF membrane and an HNT/PVDF membrane, respectively, which was attributed to the homogeneous dispersion of nanoparticles in the membrane matrix. In addition, the oil removal capacities of the membrane were improved, and all of the oil-rejection ratios were greater than 90% when the novel membrane was used to separate four different types of oil/water emulsions. The APTES-HNT/PVDF membrane showed a durable oil resistance with a flux recovery ratio (FRR) that could still reach 82.9% after three fouling/washing cycles. The enhancement of the antifouling properties was caused by a decrease of the surface roughness. As a result, APTES-HNTs will provide a new material for the fabrication of antifouling membranes for practical applications in oil/water separations.