The invention discloses a large-length-to-diameter-ratio pipeline inner wall overlap automatic polishing device. The polishing device comprises a supporting module, a traveling module, a working module and a control module, wherein the traveling module, the working module and the control module are arranged on the supporting module; the traveling module is used for moving the supporting module tothe butt welding position of a pipeline; the working module is used for polishing overlaps; and the control module is used for controlling action of the traveling module and action of the working module. According to the large-length-to-diameter-ratio pipeline inner wall overlap automatic polishing device, by arranging omnidirectional wheels and universal wheels, the polishing device can still slide laterally when moving in the left-right direction, thus, when the pipeline is rotated in the axial direction, the polishing device can be maintained at the bottom of the pipeline instead of rotating along with the pipeline, and the overlaps on the whole periphery of the butt welding position of the pipeline are removed.