The invention discloses a positioning device for a wooden pallet. The positioning device comprises a bottom frame, a bottom plate adhered to the bottom frame, a plurality of supporting columns vertically arranged on the bottom plate, top plate fixedly connected to the top ends of the supporting columns and a plurality of stretchable plates detachably connected with the top plates; the bottom plateis provided with a plurality of positioning grooves, and straight lines in the longitudinal direction of the positioning grooves are parallel to each other; the stretchable direction of any of the stretchable plates is towards the positioning grooves; the plane where the bottom plate is located and the planes where the top plates are located are parallel to the horizontal plane; the top plates are provided with a plurality of sliding grooves which are matched with the stretchable plates in a one-to-one mode to enable the stretchable plates to be detachably connected to the top plates; and a plurality of stop blocks are further hinged to the bottom plate, the stop blocks are arranged between every two adjacent positioning grooves, and the width and/or length of the stop blocks are set to be adjustable. The aesthetic degree of wooden pallet processed by the positioning device is improved, the sales of the wooden pallet are increased, and greater benefits are gained for enterprises.