The invention discloses a book end unit comprising a book end body with an L-shaped structure, the book end body comprises a bottom plate part and a vertical plate part which is integrally formed withthe bottom plate part, the book end unit further comprises a movable baffle arranged between the bottom plate part and the vertical plate part and a support positioning mechanism used for being matched with the track, the lower end of the movable baffle is connected with the bottom plate in a relatively rotatable manner, and the upper part of the movable baffle is connected with the vertical plate part through a first spring piece; in the process that the movable baffle is close to the vertical plate part of the book end body, the connecting rod drives the sliding block to move downwards, sothat the two elastic supporting arms of an elastic supporting part are forced to extend outwards, the supporting leg corresponding to each elastic supporting arm is driven to move towards the transverse outer side, the frictional resistance between the tail end of the supporting leg and the track is increased, and finally the purpose that the book end unit is positioned on the track by depending on the book is achieved, and the probability that books are poured or loosened is greatly reduced.