The utility model relates to a rust prevention polisher for outer walls of pipelines and belongs to mechanical equipment. The polisher is mainly used for rust prevention polishing of the outer walls of the pipelines and comprises a support frame and motors. The polisher is characterized in that the motors are fixedly mounted on the support frame, a limit frame and a carrier roller are fixedly mounted on the support frame, and a grinding wheel is mounted on an output shaft of each motor. The limit frame comprises support legs, support plates, bases and uprights, the bottoms of the support legs are welded to the support frame, the tops of the support legs are welded to the support plates, each support plate is provided with a plurality of mounting holes, each base is welded to the corresponding upright, and each base and the corresponding support plate are connected fixedly through a bolt. Manual operation is reduced, dust and chemical pollution is reduced, and labor efficiency is increased. The rust prevention polisher can be widely applied to industrial and civil construction installation works.