We in this paper design and implement a traditional korean medicine diagnosis system based on basic ontology. If doctors put the symptoms or tongues or pulses of a patient in the diagnosis system, they can be recommended for the diagnosis results. To support the doctors decision, the diagnosis system make the inference based on the basic ontology and compute the similarity between symptoms of patient and those of ontology. The diagnosis systems also provide the learning mechanism about diagnosis results which save the results in the ontology and reuse them in the next diagnosis. Thus, doctors can share their knowledge for the diagnosis by exchanging their ontology each other. In future, we will expand the knowledge of the basic ontology continuously so that doctors can get the more accurate diagnosis results. We also implement the prescription function and integrate it to the diagnosis system.