The invention relates to a pipeline dredging system which is applied to the technical field of pipeline dredging. The system comprises a drilling barrel, wherein a mandrel is rotationally connected tothe end of the drilling barrel, a plurality of scrapers are arranged on the mandrel in the circumferential direction, a driven gear is arranged at the end, close to the drilling barrel, of the mandrel, a driving motor is arranged in the drilling barrel, a motor shaft of the driving motor penetrates out of the drilling barrel, a driving gear meshed with the driven gear is arranged at the end, penetrating out of the drilling barrel, of the motor shaft of the driving motor, one end of the mandrel extends into the drilling barrel, a through groove which is through in the axial direction of the mandrel is formed in the mandrel, a sealing bearing is arranged at the end, located in the drilling barrel, of the groove wall of the through groove, and a water conveying pipe is arranged on the innerring of the sealing bearing. The pipeline dredging system has the effect of reducing the pipeline dredging difficulty.