Abstract: The important step towards Web service implement is the discovery of services. Traditional keywords-based Web service discovery mechanism, Universal Description, Discovery, and Integration(UDDI), lacks semantic descriptions and has low searching efficiency. We study the Web service discovery based on domain ontology. The advertisement services and requested services are described by (Ontology Web Language for Services, OWL-S OWL-S to support semantic searching. A new web services discovery algorithm based on graph matching is presented. The experiments show that the proposed algorithm can achieve better results than UDDI in precision and recall.