Virtual enterprises (VEs) are the most promising structure for future enterprises. The cooperative environment of VEs is investigated in this paper. The cooperation in a VE is a process and the depth of the cooperation and the information transparency change in different phases of the cooperation. A tri-layered cooperative structure pattern is discussed with a tri-layered cooperative process model which includes the conceptual cooperation model, the detailed cooperation model, and the executive cooperation model. Analysis of the tri-layered process modeling provides a foundation for the cooperation environment.