The invention discloses an automatic tailor-welding tool for a reel sprinkler reel wing plate. The automatic tailor-welding tool comprises a supporting underbed (1), turnover shafts (2), a workpiece supporting part (3), a welding mechanical arm (4) and an electric control device (5), wherein the supporting underbed is fixedly installed on the ground, the turnover shafts are installed on the inner side faces of the upper portion of the supporting underbed, and at least one turnover shaft is provided with a turnover driving device (21); the two ends of the workpiece supporting part are fixedly connected with the turnover shafts respectively, the workpiece supporting part comprises a workpiece supporting plate (31) of a flat plate structure, multiple pressing devices (32), multiple locating devices (33) and a hollow groove-type structure are arranged on the upper surface of the workpiece supporting plate, and the electric control device comprises an industrial control computer. The automatic tailor-welding tool for the reel sprinkler reel wing plate can achieve automatic operation, the influence on production schedule of reel wing plate by human factors is reduced, production efficiency is high, and meanwhile the tailor-welding quality of the reel wing plate can be ensured.