Cooperative design system is a new research field of Computer Supported Cooperative Work (CSCW) used in the area of engineering design. In these years although we have done many researches on cooperative design and have got many achievements, it is still urgent to study deeply in the area such as cooperative design oriented distributed problem solving, process control cooperative mechanism, system integration and so on. So this thesis is focused on studying the group decision support techniques with the distributed character for the cooperative design system.With the background of National Defence Preliminary Research Project, this thesis mainly concentrates on cooperative design system oriented distributed system structure, hierarchical models and its realization methods etc. It studies on several function modules named distributed database, modeling management for the application modules, distributed knowledge processing, distributed problem solving and synthetical evaluation for planning of projects etc. Furthermore, it realizes the integrated functional structure of intelligent agents, the data communication and information resources sharing by using middle-ware. It also brings about the system controlling tactics based on intelligent Agents and Workflow management. Finally, it builds the multi-application fields and multi-distributed objects oriented open integrated development platform for products cooperative design.The main contents and technical contributions are summed up as follows:Firstly, a distributed group decision supported system structure was put forward for the cooperative design system, making the decision support system to serve the new area of engineering design. Based on the network distributed computing mode of Client/Business/Server, it presents the hierarchical model, distributed system structure and its realized function based on multi-levels decision support techniques. It has been validated in the background project of PCDGDSS.Secondly, the process controlling tactics of distributed problem solving was put forward based on intelligent Agents. This thesis raises the multi-hierarchical knowledge representation and controlling tactics for the process objects, mixed inference mode, constitution of domain reasoning machine and its algorithm. Furthermore, it brings up the integrated framework of intelligent Agents and its blackboard-based controlling tactics for distributed problem solving.Thirdly, workflow templates were developed for application modules, realizing multi-bases cooperative working mechanism for distributed problem solving. It brings forward the cooperative design oriented model-base system by using workflow template, realizing cooperative work of different-structured database, cost analyzation model and multi-stages fuzzy synthetical evaluation algorithm.Fourthly, information resource sharing was carried out for cooperative design oriented distributed problem solving, realizing open integrated development platform for cooperative design system based on intelligent Agents.Just taking data transmission and communication threads constitution of Client/Server as an example, data communication, shared data organization, and format transformation between database files and data files for model execution were realized. Furthermore, an open integrated development platform for cooperative design system and a cooperative design oriented main executive environment for domain problem solving were presented and realized.Finally, we developed an application example of group decision support system successfully to support cooperative design, and practically validated the relative theory discussed in this thesis. Particularly, a new development approach is studied for military products cooperative design and a new field for group decision support system is broken. Multi-bases such as distributed database, model-base and knowledgebase is realized in the application example, and also a cooperative working mechanism is built for cooperative design and system integration.