The invention discloses a pipeline inner wall dredging device, and discloses a dredging device which is suitable for small-caliber pipelines, can be used for scraping and cleaning pipe walls by makingexpansion elastic pieces attached to the pipe walls and rotate and cooperates with high-pressure gas and cleaning liquid to conduct high-pressure flushing on the pipelines. The dredging device is characterized in that an inner gas pipe is arranged in a main body pipe, the two ends of the inner gas pipe penetrate out from the inside of the main body pipe respectively, a threaded pipe is connectedwith the bottom end of the inner gas pipe, a lead-in head is placed on the threaded pipe, a mounting sleeve is arranged in the middle of the top of the lead-in head, the mounting sleeve is in threadedconnection with the threaded pipe, the lead-in head is of a conical structure, the tip of the lead-in head is downward, a plurality of mounting tables are arranged on the outer side face of the bottom end of the main body pipe at equal angles, a plurality of mounting grooves are formed in the outer side face of the lead-in head at equal angles, one ends of the expansion elastic pieces are correspondingly arranged on the mounting tables one to one through connecting shafts, and the other ends of the expansion elastic pieces are correspondingly arranged in the mounting grooves one to one and connected with the lead-in head through connecting shafts.