In the present study, pure plasma and plasma-assisted catalytic activation of reforming of methane and carbon dioxide into syngas production were performed in a coaxial dielectric barrier discharge (DBD) plasma reactor at low temperature. For pure plasma, higher input power was favorable for the conversions of CH4 and CO2 but led to lower selectivities of syngas, while selectivities of syngas increased under lower flow rate of feed gases. A high CH4/CO2 ratio was more selective for C2 hydrocarbon formation. Novel g-C3N4-based catalysts were prepared and filled in the discharge gap at low temperature. The cooperation effect of DBD plasma with g-C3N4 catalyst was achieved that contributed more to the activation of carbon dioxide than that of methane as well as the yield of CO for its low reduction potential. TiO2/g-C3N4 with heterogeneous structure as packing the catalyst bulks into the discharge zone was capable of further improving the reforming of methane and carbon dioxide. TiO2 mass ratio exhibited significant effect on dry reforming reactions and only TiO2/g-C3N4 with 1% TiO2 mass ratio presented enhanced hybrid effect than that of g-C3N4 catalyst.