Creation and development of formal domain ontology of Occupational Therapy (OTO) requires the prescription and formal evaluation of the results through specific criteria. UPON Methontology of development ontologies was followed to create OTO ontology, and was implemented by using Protégé-OWL. Accuracy of OTO ontology was assessed using a set of ontology design criteria. This paper describes a software engineering approach to model domain ontology for occupational therapy resources (OTO) using Natural Language Programming (NLP) technology. The rules were written to annotate the domain concepts using Java Annotation Patterns Engine (JAPE) grammar. It is used to support regular expression matching and thus annotate OT concepts by using the GATE developer tool. This speeds up the time-consuming development of the ontology, which is important for experts in the domain who face time constraints and high workloads. The rules provide significant results: the pattern matching of OT concepts based on the lookup list produced 403 correct concepts and the accuracy was generally higher. Using NLP technique is a good approach to reducing the domain expert’s work, and the results can be evaluated. This study contributes to the understanding of ontology development and evaluation methods to address the knowledge gap of using ontology in the decision support system component of occupational therapy.