The invention discloses a tail positioning and assembling tool in a wheeled vehicle body assembling and welding production line, belongs to the technical field of wheeled vehicle positioning and assembling, and aims to solve the problems that in the prior art, the assembling error is large, and the yield of finished products is influenced. The tail positioning and assembling tool in the wheeled vehicle body assembling and welding production line comprises a positioning device and a position adjusting device, wherein the positioning device is matched with a vehicle tail to achieve positioning,and the position adjusting device drives the positioning device and the vehicle tail to integrally achieve adjustment in the directions of +/-x axis and +/-y axis and rotation around the x axis. The positioning device comprises a positioning plate and a clamping and positioning device, wherein the positioning plate comprises an end plate and a straight plate, one end of the straight plate is fixedly connected with the end plate, and the clamping and positioning device is arranged on the positioning plate and matched with the positioning plate to achieve positioning and clamping of the vehicletail. According to the design, the positioning and assembling efficiency of a vehicle tail workpiece and a previous station assembly is greatly improved, the assembling error caused by various reasonsis reduced, the automation level is improved, and the labor cost is reduced.