In this paper we propose a bio-ontology construction method using object-oriented paradigm. This method is simple yet shows powerful semantic expressiveness. The sophisticated bio-ontology is built by an intuitive manner reasoning subtle semantics inherently existing between complicated and informative terms. The result of the reasoning is used not only to recommend candidate terms to be linked by relationships but also to answer user queries against the bio-ontology. Its recommendation facility based on inheritance makes it possible to incrementally refine relationships between terms. The method is supported by object-oriented ontology manager (OOM) which treats terms as objects, and thus sub objects inherit properties from super objects. The constructed bio-ontology can be translated into a standard ontology language, RDF/RDFS by a translator in OOM to be easily extended, modified, and reused blending with other external ontologies.