Web IR presents a new challenge due to the heterogeneity,the dynamic characteristic and the size of theWeb. A practical IR system that can satisfy the users' demand is very important ,in this paper we research the charac-teristics of Web IR in detail and give out the ideal Web IR service model:it should include search engine spectrum,search engine hierarchy,search engine cooperative network. We also analyze the key technique of this model,propose asimple way for the Web IR service to deal with the huge-scale of Web resources easily,and test part of the ideas in ourprototype system SAInSE.
