The recent explosion of the new design optimization knowledge and advanced computer technology has laid the foundation for the emerging fields of distributed multidisciplinary design optimization (MDO). The challenge now faced by designers is to effectively use this vast amount of knowledge. There are many software tools available in each design area. However, the key problem is how to integrate these tools and databases, which conform to different interface and requirements with little consideration to integration and reusability, in a flexible and robust way. This work proposes a novel ontology-based semantic integration framework for cooperative distributed MDO environments. The semantic integration aspect will provide the foundation for service-oriented architecture for distributed MDO environments. The cooperation aspect will focus on seamless integration among autonomous MDO systems in dynamic open environment, using multi-agent paradigm.