Barium additive, which can resutt in a varistor character. was doped in the usual ZnO-Bi2O3-Sb2O3 varistor ceramics. It was found that a new grain boundary phase which is barium meta antimonate (BaSbA) crystal phase dissolving other trace compositions was formed besides the known Bi2O3 and Ｚｎ2．３３Ｓｂ０．６７Ｏ4 grain boundary phases. It was also found that the ＢａＳｂ2Ｏ6 phase is thermally stable and it plays an important role in improving the degradation properties of the varistor ceramics. The anti-degradation abilities of the varistor ceramics under the long duration load voltage and the surge current are both enhanced obviously when the amount of the Bi2O3, Ｚｎ2．３３Ｓｂ０．６７Ｏ4 and ＢａＳｂ2Ｏ6 grain boundary phases are in an appropriate ratio by controlling the amount of various additives. It is particularly valuable that the degradation properties of the V-I characteristics in backward direction are improved significantly.