CO2 decomposition to CO and O2 was investigated in a dielectric-barrier discharge (DBD) reactor packed with BaTiO3 balls, glass beads with different sizes, and a mixture of a Ni/SiO2 catalyst and BaTiO3 balls at lower temperatures and ambient pressure. The property of packing beads and the reactor configuration affected the reaction significantly. The Ni/SiO2 catalyst samples were characterized by SEM, XRD, BET, and TEM. The combination of a DBD plasma and a Ni/SiO2 catalyst can enhance CO2 decomposition apparently, and a reaction mechanism of the plasma assisted CO2 dissociation over the catalyst was proposed. In comparison with the result packed with glass balls (3 mm), the combination of BaTiO3 beads (3 mm) with a stainless steel mesh significantly enhanced the CO2 conversion and energy efficiency by a factor of 14.8, and that with a Ni/SiO2 catalyst by a factor of 11.5 in a DBD plasma at a specific input energy (SIE) of 55.2 kJ/L and low temperatures (<115 °C).