The invention provides a bookbinding method and device. The method includes the steps of: determining a current page number of a small page or a large version and a total page number of a document, which the small page or large version belongs to; constructing the current page number and the total page number into a character string; adding and reflecting a bar code produced from the character string to the small page or the large version; printing the small page or the large version to output the printing paper; reading bar code on the printing paper by a binding machine; and conducting classification binding on the printing paper by the binding machine according to the bar code. The invention simplifies the manual operation and avoids man-made error.