Cooperation has become the principal way in which creative activities are carried out in modern society. Previous research has shown that in the cooperation of creative activities (i.e., co-creation), different participants can play two completely different roles: some participants are the originators who generate initial contents, and others are the revisors who provide revisions or coordination. In this research, we investigated the different participants’ roles (i.e., the originator vs the revisor) in co-creations and how these roles affected the final cooperation-group outcome. By using cooperation networks to represent the cooperative relationships among participants, we found that peripheral members (i.e., those in the periphery of the co-operation networks) and core members (i.e., those in the centre of the co-operation networks) played the roles of originators and revisors, respectively, mainly affecting the quantity versus the quality of creative outcomes. These results were robust across three different datasets and three different indicators defining core and peripheral members. Our results uncover the cooperation pattern in co-creations and advance the understanding of how co-creations occur in networks.