Web ontologies as the foundation of the Semantic Web were proposed to solve the problem of integrating and sharing heterogeneous information resources in the Web. Massive amount of domain specific ontologies have been constructed and published in different domains on the Web. However, several limitations make existent ontologies not suitable for high-level and large-scale applications. In this paper, we described a context-based ontology service with a large-scale Traditional Chinese Medicine (TCM) ontology, which provides clients with an interactive interface and intelligent inter-operations to assist users in sharing and exploiting large-scale TCM information and can be used as a semantic view for domain specific problem solving.