Complex product design is a knowledge-intensive process that involves various aspects of technical knowledge and experience. This paper contends that the conventional Product Data Management (PDM) system has some inherent limitations due to its original intention to manage processes and results, not to manage and reuse knowledge. Therefore, to overcome the shortage that knowledge cannot be discovered and reused effectively in PDM systems, a “Domain Ontology - Index Knowledge – Data Resource” (OKD) three-layer mapping model is proposed to organize DK. The key idea behind our approach is a flexible ontology-based schema that domain ontology is used as semantic model and index knowledge as data indexing to enable the capture and reuse of problem-solving knowledge to improve PDM’s performance. Finally, conclusion is made.