In this study, ZnO-Bi2O3-based multilayer varistors (MLVs) cofired with nickel (Ni) inner electrodes were prepared by tape-casting method. Samples were sintered in pure nitrogen (N-2) to keep Ni from being oxidized, and then reoxidized in air to obtain the nonlinear properties (reduction-reoxidation method). The EDAX results showed that Ni inner electrodes are stable and have no evident migration into ZnO-Bi2O3-based ceramics when sintered in N-2. The influence of reoxidation temperature on microstructures and nonlinear properties of samples were studied. Samples reoxidized at the temperatures lower than 650 degrees C showed poor nonlinear properties. After reoxidized in air at 700 degrees C for 2hours, samples exhibited nonlinear properties of V-1mA=16.3V, =26.5, I-L=0.68A. At the reoxidation temperature higher than 750 degrees C, the oxidation of Ni inner electrodes deteriorated the nonlinear properties of samples. It demonstrated that ZnO-Bi2O3-based MLVs with base metal Ni inner electrodes proposed in this work are suitable for reduction-reoxidation method. The replacement of noble metals Pt or Ag/Pd alloys by base metal Ni is expected to lower the cost of ZnO-Bi2O3-based MLVs.