This study investigated the influence of codoping with Ge and GeO2 on the nonlinear coefficient and the breakdown voltage E-B of TiO2-Nb2O5-SrCO3 varistor ceramics. Ge-GeO2 codoping notably changed the microstructure of the TiO2-Nb2O5-SrCO3 ceramics, increased , and decreased E-B. When the doping contents of Nb2O5 and SrCO3 were 0.1 and 0.2mol%, respectively, the optimum doping content of 0.25mol% Ge and 0.75mol% GeO2 exhibited high (11.6), low E-B (13.8V/mm), and high grain-boundary barrier phi(B) (0.96eV). These results are superior to previous findings. In addition, Ge and GeO2, which function as sintering aids, reduced the sintering temperature caused by the low melting point. The optimal sintering temperature was 1260 degrees C for the TiO2-Nb2O5-SrCO3 ceramics doped with Ge and GeO2.