Abstract: Ontology is a formal explicit specification of a shared conceptualization．Modeling social network information with ontology can provide an entitative understanding of impersonal existence, which makes full use of the advantages of ontology on denoting and organizing information．This paper proposes a domain ontologies model focusing on social network information,which abstracts the impersonal existences in social network information domain into three primary ontologies：actor, relation network and group．The model is suitable for describing all kinds of social network analysis and visualization methods,therefore supports information visualization applications of social network． According to the requirements of social network structure analysis,the group analysis method based on regular equivalence group and the force-directed layout algorithm based on group and role analysis under this ontology model have been presented．Then the paper illustrates the application of this domain ontology model and the analysis and visualization methods by studying the case of terrorist information．