How to quickly and cheaply construct Web ontologies has become a key technology to enable the Semantic Web. However, information imprecision and uncertainty exist in many real-world applications. Thus constructing fuzzy ontology by extracting domain knowledge from fuzzy database model such as fuzzy ER model can profitably support fuzzy ontology development. In this paper, firstly, we give the formal definition and semantics of fuzzy ER model. Then, we introduce a kind of fuzzy extension of OWL DL, named fuzzy OWL DL. Furthermore, based on the fuzzy OWL DL, the formal definition and Model-Theoretic semantics of fuzzy OWL DL ontology are given. What’s more, we realize the formal translation from fuzzy ER model to fuzzy OWL DL ontology by a semantics-preserving translation algorithm. Finally, since a fuzzy OWL DL ontology is being equivalent to a description logic f-SHOIN(D) knowledge base, the reasoning problem of satisfiability, subsumption, and redundancy of fuzzy ER model may reason automatically through reasoning mechanism of f-SHOIN(D) is also investigated, which can contribute to constructing fuzzy OWL DL ontologys exactly that meet application’s needs.