To overcome the deficiency in sharing and reusing design knowledge in manufacturing industry, a strategy based on functional ontology was proposed for design knowledge-sharing. The existing product structure can be mapped to its product functions by using functional ontology, and the design principles can be represented by functional decomposition tree. First, the basic framework of functional ontology was introduced. Then, the role of the functional decomposition tree to product design was analyzed. Finally, a knowledge-sharing platform for household appliances was designed and developed based on functional ontology. It was used to verify the proposed strategy. The experimental results show that the proposed strategy can effectively realize information retrieval, sharing and reuse of design knowledge in manufacturing industry. It can also shorten product development cycles.