Dredging system of sewage pipeline with large-pipe diameter

The invention relates to a dredging system of a sewage pipeline with large-pipe diameter and a method thereof. The dredging system comprises a small downhole dredger, an overground operation system, an air-charged rubber gate and an overground charging-discharging device. The small downhole dredger comprises a dredger body and an underwater stirring device arranged on the dredger body; the small downhole dredger is connected with a ground operation control system through a rope and a control line; when in operation, the underwater stirring device stirs up sludge at the bottom of a pipeline. Before small downhole dredger works, the air-charged rubber gate is placed in a downstream pipeline of a dredged pipe section and charged with air so as to lead water level in the dredged pipe section to rise up, thus facilitating the operation of the small downhole dredger. On the ground, an operation system is arranged so as to control the operation of the small downhole dredger in the pipeline. After accomplishing the operation in one pipe section, the small downhole dredger is lifted out from the pipeline, simultaneously the air in the air-charged rubber gate is discharged and the rubber gate is taken out from the pipeline. Former sewage accumulated in a working pipeline flows away fast and the sludge stirred up is also washed away together, thus removing the sludge in the pipeline. Thedredging system can realize dredging of the sewage pipeline with large-pipe diameter; and the diameter of the dredged pipeline is over 1meter, in addition, the operation done by workers in the pipe is not needed, and the device has strong processing capability, small volume, flexibility, low cost and operation expense, and simple technology.