The invention discloses a positioning device with a buffer structure. The positioning device comprises a support and a positioning structure located on the support. The support comprises a supporting frame at the bottom and a lifting frame installed on the supporting frame. A transverse sliding groove is formed in the top of the supporting frame. The lifting frame moves on the supporting frame through a sliding block in cooperation with the sliding groove. Lifting grooves are formed in the side faces of the two sides of the lifting frame. A left lifting block is arranged in the lifting groove in the left side. A right lifting block is arranged in the lifting groove in the right side. The left lifting block and the right lifting block are made of magnetic materials and attract each other through the magnetic force. A shaft hole is formed in the right lifting block, and the right lifting block is connected with the positioning structure through the shaft hole. The positioning structure comprises a cavity and a connecting shaft penetrating through the cavity in the axial direction. A positioning block is installed on the connecting shaft.