The invention discloses a method and a system for describing an extensible marking language of a document. The method comprises the following steps of: converting an input document into a portable document format at first; extracting page size information and a preview image of each page of the document to generate an information unit taking page as a unit; and on the basis of pages, organizing a plurality of pages into virtual pages by using the extensible marking language, and organizing the virtual pages to form a virtual document, wherein only one new virtual document is generated aiming at folding and assembling operations of the document. The method and the system are mainly used in the field of digital printing.