To solve the lack of rationality in the aircraft survivability evaluation index system, the method of solving the potential correlation among the evaluation indices is proposed. Taking the survivability data in the literature for example, under different confidence level we use fuzzy cluster method to classify again the original 10 original evaluation indices, according to the efficient index defined, the best number of the cluster is 4. Then the 4 new evaluation indices are analyzed by factor analysis to prove the result of fuzzy cluster, thus the relation between the new indices and the original indices is acquired. The result shows that the new index system is simple and effective, compared with the old one, its fuzzy cluster method is rational and its effect is good, so the method can be applied in the establishment of evaluation index system for aircraft survivability.