A Ni/SiO2 catalyst was prepared by the plasma decomposition of a nickel precursor via dielectric barrier discharge (DBD). The obtained Ni/SiO2 catalyst shows an enhanced H2S resistance for methanation of syngas (CO + H2). The plasma decomposition has a significant influence on the structural property of Ni/SiO2. The plasma decomposed catalyst shows less defect sites on Ni particles. The formation of Ni-sulfur species was effectively inhibited. The mechanism of H2S poisoning on different catalysts with and without plasma decomposition was also discussed according to the reaction temperature.