Abstract: Retrieving the information of products by product features is a knowledge based process, being supported by knowledge-base. However, expressing knowledge by computer understandable semantics and quantifying product features are the key parts of a knowledge-base. A method to describe the quantified functional characteristics of product based on customer's criteria is developed. A comprehensive description of product and query requirements by attribute theory is worked out. Finally, a system that searches designing knowledge based on product characteristics and runs in web environment is developed. Designers can acquire reliable designing knowledge according to the matching degree.