In the equipment developing stage, the expense of equipment developing cost is an important part of the equipment life cycle cost, and has a significant influence on the whole life cycle cost, this paper presents a new model which can help the decision-maker accounting the expense of equipment developing cost. In light of Vague sets, the meaning and fuzzy entropy of Vague sets are described. Based on the characters of Vague sets that can deal with the fuzzy information exactly, a new annuity distributive model of equipment developing cost is advanced. In using the model, the judgment matrix is first established by the experts, and then handled quantitatively. Based on the results obtained the fuzzy entropy of Vague sets is calculated. Finally, the fuzzy entropy of Vague sets is used to determine the development cost of equipment weights and the amount of annuity. A practical example shows that the model is reasonable and effective. This model can be used as a reference when decision makers distributing capital, so it is of a certain practical value.