Due to the lack of supporting service composition by UDDI and WSDL, a method based on template and extended WSDL to compose web services, is presented. By this method, domain experts design templates in advance to achieve the reusability of business service components, and also make it possible to allow the end user to request the service transparently. The templates are described by extended WSDL to transmit on networks, and are parsed to graphs for template matching in internal template library. The template matching algorithm, how this method works, and the API of template library are introduced.