For the representation and reasoning of fuzzy knowledge for domain ontology, the paper presents the reasoning method based on fuzzy ontology. On a basis of the study of civil aviation emergency domain ontology, it gives fuzzy extension model of domain ontology based on fuzzy description logic from the perspectives of fuzzy modifiers and fuzzy concrete domains, and designs fuzzy rules by introducing weight concept and gives the representation and construction process of fuzzy rules on a basis of f-SWRL in connection with the inference application of situation analysis for civil aviation events. The experimental results show that the fuzzy extension method of domain ontology can make up for the issue that the existing domain ontology is inadequate in terms of fuzzy knowledge representation, and provide a good methodological support for making domain ontology perfect and inference application with the reasoning implementation based on fuzzy rules.