The invention discloses a library book automatic tidying device and mainly relates to the field of library equipment. The library book automatic tidying device comprises a translation mechanism and alifting mechanism which are used for positioning an executing mechanism to a corresponding book rack grid, wherein the executing mechanism comprises an installation rack, the installation rack is provided with a sliding rack capable of advancing towards a book rack, the sliding rack is provided with a supporting plate, protection plates and a baffle which are used for placing, scanning and identifying books, a book spine position is further provided with a pushing plate capable of pushing forwards and retreating, the parts, close to the front side of the book rack, of the protection plates areprovided with elastic pieces, and the front sides of the elastic pieces are closed and provided with magnetic snaps. According to the library book automatic tidying device, by means of mechanized cyclic motions, the process of tidying and position returning on the books manually is replaced, a lot of labor and labor time are saved, position returning is performed accurately and rapidly, various operating costs are significantly saved, and realization of a warehousing, intelligent, mechanized book management system is facilitated.