Using a Ni/polyamideimide sol as a template, a nanoporous carbon membrane was prepared in a single coating by means of a novel technique: the carbonization of a nickel-containing polyamideimide precursor combined with the catalytic decomposition of methane in a nitrogen atmosphere. The separation performance of the membrane was significantly better than that fabricated by a single coating and conventional pyrolysis, even as good as or better than those for three-coating carbon membranes. This procedure significantly reduced the cost of the membrane production and provided a promising technical way for the preparation of carbon membrane. The surface and cross-sectional morphologies, the composition, and the microstructure of the carbon membranes were characterized by means of SEM-EDX, AFM, and XRD techniques. The properties of the precursor and membranes were investigated by FT-IR absorption spectra and H-2-TPD.