The Index information in insulator condition evaluation has the characteristics of fuzziness, randomness and greyness. In view of the fact that the current evaluation methods seldom consider the greyness of index information, a grey fuzzy comprehensive evaluation model of contamination state for insulators is proposed based on IFAHP with Bayesian modified method by combining grey fuzzy theory and grey cloud model. In the proposed method, IFAHP method and intuitionistic fuzzy entropy theory are introduced for the first time to determine the weight set of evaluation factors more scientifically and suitably, and optimization model of subjective weight is established based on Bayesian formula to realize two-stage weighting of index. Moreover, the grey cloud model is used to obtain the correlation degree of each state level of indexes, which is act as the module part of the judgment matrix. And the grey part of matrix is use to take into account the grey characteristic of evaluation information, and then the established evaluation matrix is comprehensively processed. Finally, the analysis and comparison of cases show that the weight set determined by IFAHP with Bayesian modified method is more reasonable and applicable, and the result based on grey fuzzy evaluation is closer to the actual situation.