Ontology-based test case reduction in regression testing during software testing is a sophisticated approach that leverages semantic knowledge representation to optimize the selection of test cases. By harnessing domain-specific ontologies, this methodology facilitates a more intelligent and efficient reduction process, ensuring that only the most relevant test cases are retained for subsequent testing cycles. This research paper explores the application of ontology-based technique to enhance the efficiency of regression testing in software development. By leveraging ontological knowledge representations, the study introduces a novel approach for reducing the number of test cases while preserving test coverage, thereby significantly optimizing the regression testing process. The proposed framework not only streamlines testing efforts but also enhances the overall quality assurance of software systems, making it a valuable contribution to software engineering practices.