—At present, Web services are created and updated on the fly. It has already beyond the human ability to analysis them and generate the composition plan manually. It is a problem that composing existing Web services automatically and dynamically according to users’ request. A number of approaches have been proposed to tackle that problem. Most of them are inspired by the researches in cross-enterprise workflow and AI planning. In this paper, we propose a Web services composition method based on OWL ontology, and design a system model for services composition. Web services are modeled based on OWL ontology, the services are semantically matched and composed, and the executing plan is generated. Finally, the plan is executed and valuable results are returned to users. We also provide the experimental comparison, and report that our method has more accurate matching results.