In this work, The Electrical behaviour of ZnO based varistor is improved. On using the classical proceeding for fabricating the ceramic for Electronic, we have prepared different samples with different oxide additives such as (Bi2O3, Nb2O5, MnO2, Co3O4, Cr2O3, NiO,Ce2O3, and La2O3). We have got several lots, each of one represents one sample. We have optimized the percentage of the impurity as following: On varying the impurity percentage, we have obtained different values of the nonlinearity coefficient (a) for every sample. The greatest value of, a, corresponding to the best value of the proportion of the impurity which will be used in the final composition. Finally, we have mixed all best values together so we got a new sample, Our results explore that the value of (a) in the new sample is increased Significantly to a value of (100 +/- 2) and the non-linear region of the I-V characteristic of the varistor was improved. After that we measured the I-V characteristics of new sample at various temperatures to explore the effect of varying temperature on electrical properties on ZnO varistors. (C) 2012 Published by Elsevier Ltd. Selection and/or peer-review review under responsibility of The TerraGreen Society.