This paper firstly discussed the definition of knowledge integration in the field of product development and proposed the multidimensional knowledge integration model which could be the guidance during the implementation of knowledge integration. Subsequently the framework of knowledge integration is presented, three layer (the enterprise distributes resources layer, enterprise managed knowledge layer and product development process layer) in the framework are explanted respectively. The ontology is introduced to provide the semantic fundament for the framework. The structure of integrative ontology is studied and constructed with OWL(Ontology Web Language). The ontology plays an important role in knowledge organization and knowledge service and it’s the core part of the whole framework. At last a prototype system based on the previous techniques is developed and basically fulfills knowledge integration in product development process.