To realize integration, organization and reusability of knowledge related to COVID-19, an ontology for COVID-19 (CIDO-COVID-19) was constructed which extended the Coronavirus Infectious Disease Ontology (CIDO) by adding terms of COVID-19 related to symptoms, prevention, drugs and clinical domains. First, terms from the existing ontologies, literature, clinical guidelines and other resources about COVID-19 were merged. Then, the Stanford seven-step approach was used to define and organize the acquired terms. Finally, the CIDO-COVID-19 was built on basis of the terms mentioned above using Proté gé . The CIDO-COVID-19 is a more comprehensive ontology for COVID-19, covering multiple areas in the domain of COVID-19, including disease, diagnosis, etiology, virus, transmission, symptom, treatment, drug and prevention.