Semantic web is to extend the current human readable web to encoding some of the semantic of resources in a machine processing form. As a semantic web component, Semantic Web Services (SWS) uses a mark-up that makes the data into detailed and sophisticated machine readable way. One such language is Ontology Web Language (OWL). Existing conventional web service annotation can be changed to semantic web service by mapping Web Service Description Language (WSDL) with the semantic annotation of OWL-S. In this conversion of WSDL to OWL process, the ontology plays a vital role.