Abstract: As fuzzy ontologies arc widely used in describing fuzzy information in the Semantic Web, how to efficiently store fuzzy ontologies is becoming a more important research issue in the domain of the Semantic Web. An approach to store fuzzy ontologies based on relational databases was proposed by making use of the advantage of organizing and managing data of relational databases. Firstly, a method of representing fuzzy datatypes was introduced by fuzzy extending of the RDF datatypes. Then, the storage schema of fuzzy ontologies using relational databases was presented. On this basis,the storage processes of the fuzzy ontologics structure and instances were given. Finally, the correctness of the stotage schema of fuzzy ontologies was proved. The approach of storing fuzzy ontologics in relational databases provides an efficient solution to the storage and management of fuzzy data in the Semantic Web.

Key words: Semantic Web, Fuzzy ontologies, Relational databases, Storage, Information capacity