Abstract: The explosion of information on the Web turns the search for interested information from the Web into a great challenge The system called Web data engine—SESQ（Search Extract Storage Query） is designed to solve this problem by using the specific domain ontology to search, extract, store and query the domain Web data In contrast with traditional database systems and search engines, SESQ is different in data model, query expression, data storage schema, and the use of index So a new query processing scheme is needed to tackle these features In SESQ, a query optimizing scheme based on the underlying storage schema is proposed It is proved that the scheme is very efficient by experiments because it could predict the data that will not make any contribution to the final query result