Abstract: The Hall for Workshop of Metasynthetie Engineering(HWME) is an engeering technology proposed for coping with open complex giant systems. In this paper we describe the implementation of a human-computer-cooperated intelligent information system with HWME and multiagents. We propose a layered model, a system structure over the network, and a distributed computing model--an n-tier client/agent/server-nested Requester-Mediator-Provider--for building the system. Furthermore, we discuss the framework and working mechanisms of an agent-based system of HWME, which is designed for macroeconomic decision-support based on intelligent information agents in Java. Our system implementation shows that an agent-oriented HWME system over the Internet may exhibit better performance in terms of handling open complex problems.