The aggregation method for a large-scale group decision making problem is studied. Firstly, the grey cluster
method is used to reduce the negotiation difficulty of a group. Based on the transformation formula of a linguistic evaluation,
the method on the weight of criteria inside of the group is developed according to the difference of the group. Then the
integration preference of each category is measured. A method of the weight of category is proposed and the group preference
aggregation model is established based on the smallest deviation object among the categories. The consensus degree of
decision maker is defined. Furthermore, the coordination method is proposed to achieve the coherent result of the group. The
example analysis shows the steps and the feasibility of the proposed method.