Whether a decision group does its function or not directly depends on the rationality of its characters. The decision science, also with other correlation disciplines, wants to know how the group characters affect the group performance. Although there are great deals of means to describe the group characters theoretically and practically, in this paper, we consider that the integrity character of a group is composed of the group scale, the constitution and the structure. So the research on how group characters affect the group performance should focus on the three aspects. In order to grasp the present research situation and clear the prospective direction of the studies, we will summarize the study on how the group characters affect the group performance from these three aspects.
