For a fuzzy object, the decision maker not only wants to know the results of the comprehensive evaluation, but also wants to know the ineffective reason and the improvement strategy for a fuzzy event. When the method of fuzzy comprehensive evaluation is applied, the method can only provide the result of fuzzy comprehensive evaluation, but it can not provide the ineffective reason of the result and the possible improvement method. In order to further enhance the ability of the fuzzy comprehensive evaluation method, based on the original data information that is used by the fuzzy comprehensive evaluation method, the concept of fuzzy possibility set and fuzzy efficiency are given. At the same time, the corresponding mathematical model is proposed, these models can not only find out the ineffective reason of the fuzzy object, but also provide many useful information for improving the fuzzy object.