Abstract: Whether is a group decision making scientific or not depends mainly on the effect of group decision making.Taking into account the efficiency and quality of group decision making,an index system for objective evaluation for the effect of group decision making is established,and the weight of each index is considered.A synthetic assessment model based on the attribute measure theory is built up,and a numerical example is given by the proposed method.The result shows that the attribute measure theory using the criterion of degree of confidence can avoid the occurance of unreasonable classification like fuzzy synthetic assessment,etc.