Depending on current sharing and energy sharing requirements of non-linear de-excitation resistance in large generators， based on the traditional characteristics of ZnO non-linear resistance， this paper proposes a group of new coefficients from a given statistical category which can reflect the consistency of non-linear de-excitation resistance group， that is coefficient of variation and coefficient of range. By collection and analysis of non-linear resistance data with the given coefficient， several sets of ZnO resistance are evaluated and analyzed. At last recommendation about coefficient of variation and coefficient of range indicators are proposed. A proposal to include the given coefficient in the system for assessment and examination is advised. It is believed that the method proposed in this paper is valuable safety evaluation of non-linear de-excitation resistance in large generators.