To solve the problem of chaining distributed geographic information Web services （GI Web services）, this paper provides an ontology-based method. With this method, semantic service description can be achieved by semantic annotation of the elements in a Web service description language（WSDL） document with concepts of geographic ontology, and then a common under-standing about service semantics between customers and providers of Web services is built. Based on the decomposition and formalization of customer requirements, the discovery, composition and execution of GI Web services are explained in detail, and then a chaining of GI Web services is built and used to achieve the customer＇s requirement. Finally, an example based on Web ontology language for service （OWL-S） is provided for testing the feasibility of this method.
