1. A method for establishing relationship between documents in term of a user's operation upon a document search result, wherein the document search result is obtained from a search based on one or more search queries, the method comprising: monitoring the user's operation upon the document search result; obtaining one or more documents selected by the user according to the operation and storing a related document list for the selected documents, and depicting a document relationship according to the related document list by using at least the one or more search queries.