As products become more complex, short-life cycled and customized, the design efforts require more knowledge-intensive, collaborative, coordinating, and information sharing. By sharing knowledge, information, component and process across different families of products, the product realization process will be more efficient, cost-effective and quick-responsive. The purpose of this paper is to propose an ontology-based product family modeling framework. The ideas of product family, ontology and Semantic Web were investigated in depth. A Semantic Web is originally defined as a web of data that can be processed directly or indirectly by machines, which operates intelligently. A Web Ontology Language (OWL) is designed for use by applications that need to process the content of information instead of just presenting information to humans. For the selected cellular phone product family, ontology was constructed and implemented using prot$acute{e}$g$acute{e}$-2000.