Component-based development is an approach to developing a software system by assembling and composing already built software components. For component-based development to be successful, one of the key requirements is an effective scheme for classifying and describing them in detail, as well as a corresponding repository for storing and retrieving these components. This paper proposes an ontology-based software component description scheme with owl web ontology language. In this scheme, the component description information that is provided by user is associated with ontology to present semantic meaning, which builds the foundation for semantic reasoning in the component retrieval process. The semantic-based software component retrieval system is also constructed in this paper. This approach can retrieve component based on semantic description of the components. The whole approach extends the software reusable library to the World Wide Web. In the retrieval process, a user query in natural language is translated into web ontology language representation formats in order to augment retrieval recall and precision by deploying the same semantic representation technologies on both the user query side and the component side.