The invention provides an SCARA (selective compliance assembly robot arm) robot special for welding operation. The SCARA robot comprises a base, a large swing arm, and a small swing arm. A fixed shaft is disposed at the top of the base. The center-of-gravity part of the large swing arm is mounted on the fixed shaft in a sleeving manner and is rotatably connected with the fixed shaft. One end of the small swing arm is hinged to the large swing arm through a rotating shaft fixed to the small swing arm; the other end of the small swing arm is connected with a sleeve which is vertically arranged and which can move up and down relative to the small swing arm; a vertical shaft rotatably connected relative to the sleeve penetrates the sleeve; a welding torch head fixture is hinged to the lower end of the vertical shaft. The SCARA robot has the advantages that welding can be performed by the robot instead of manual operation, the problems that severe welding environment and toxic matters may impair the health of workers, welding quality is unstable and production efficiency is low are overcome, intensity of welding is reduced for workers, and the SCARA robot is simple in structure, low in manufacturing cost and high in welding precision, has large operating space, allows accurate positioning, has good compliance, and responds fast.