Abstract: The Semantic Web is expected to process fuzzy concept knowledge and data type information in an intelligent and automatic way. Recent research has shown that OWL has some serious limitations; i. e.，it can't process imprecise and uncertain information which widely exists in the Semantic Web and ontology; furthermore, it does not support customized data types and customized data type predicates. In this paper, we made the following two contributions to solve the above limitations; (i) presented a new kind of fuzzy description logic F-SHOIN(G),and gave its syntax and seman-tics; (ii) extended OWL to f-OWL by recoding the description norms of OWL，based on F-SHOIN(G) and the syntax specification of RDF/XML. f-OWL can not only support the representation of fuzzy concept knowledge, but also fuzzy data information with customized fuzzy data types and customized fuzzy data type predicates. It provides a new representation method for the investigation of ontology.

Key words: Semantic Web, Fuzzy description logic, F-SHOIN(G) , Fuzzy OWL, Customized data type