Ontologisms have been applied to many applications in recent years, especially on sematic web, information retrieval, information extraction and question and answer. The purpose of domain-specific ontology is to get rid of conceptual and terminological confusion. It accomplishes this by specifying a set of generic concepts that characterizes the domain as well as their definitions and interrelationships. This paper will describe some algorithms for identifying semantic relations and constructing information technology ontology, while extracting the concepts and objects from different sources.