The influence of Nb2O5 doping and pre-sintering of Nb2O5 with ZnO on electrical and pulse degradation characteristics of ZnO varistors has been investigated. Doping with a small amount of Nb2O5 worsened the electrical and pulse degradation characteristics. However, with 0.05-0.1 mol% Nb2O5, the electrical and pulse degradation characteristics were greatly improved, but further doping with Nb2O5 had little influence. Pre-sintering of Nb2O5 With ZnO at 1000-1100 degrees C greatly improved the electrical and pulse degradation characteristics.