Abstract: Virtual organizations are becoming an important form for cooperation among regular organizations （or persons）, which needs the support of integrative information infrastructure. In this paper, an agent based integrative framework for virtual organizations, called IFVO is introduced, which, using joint intentions as the main means, supports the development and coordinated running of integrative information infrastructure for virtual organizations in three aspects: architecture style, agent cooperation, and semantic interaction. IFVO allows the infrastructure of a virtual organization to be packed and constructed into the nested agent federation which can be composed and decomposed quickly, in order to support effectively the dynamic creation of virtual organizations, the reengineering of business processes, and the coordination of cooperation processes.