Abstract: The SrTiO₃-based capacitor-varistor (C-V) ceramic materials were prepared by carbon reducing single-fired process and the effects of donor Nb⁵⁺, acceptor Mn²⁺ on the properties of the materials were studied. High dielectric constant and low resistivity were obtained when 0.6 mol% Nb₂O₅ were doped. The addition of Mn₂₊ attributed to the forming of grain-boundary barrier and could improve nonlinear coefficient of samples, C-V ceramics with good performance cold be obtained with 0.05-0.06 mol% Mn(NO₃)₂ added. Samples sintered by carbon reducing single-fired mechanism could accelerate the process of grain growth and obtain better dielectric properties than that sintered in air.