Commercial Off-The-Shelf (COTS) software products are increasingly used as software components in large-scale systems. We had proposed an approach for distributed COTS software integration by using the concepts of multi-agent system and distributed scripting mechanism. To describe the experience in the COTS software integration and facilitate the reuse of the software integration procedure, this paper presents a multi-agent architecture for the COTS software integration systems. This architecture is of a threelayered structure and is described with the Agent UML (AUML). Since the interaction and internal processing of agents is clearly described in the proposed architecture, programmers may have a guide to build a software system and implement the protocols and behaviors of agents according to the three-layered description. To illustrate the use of the proposed architecture, an example system is also experimented in our study.