Web services management and organizing technologies based on syntax level can not meet the need of getting relevant information,responding to diversity service request and reusing Web services in information grid.In this paper,a Web service dynamic integrating and constructing(WS-DIC)strategy based on ontology for information grid is proposed.By the ontology and its reasoning capability,WS-DIC can reuse existing Web services to generate an optimized integrating or constructing paths set to meet the need of request diversity and information relevancy.By the abstraction and formalized model of WS-DIC,the regulation and arithmetic of dynamic integration and reconstruction is discussed.Experimenters indicate that WS-DIC can effectively get the optimized integrating or constructing path and get more advantage then full-text search and SQL query.