Hydraulic sewerage dredger

Disclosed is a hydraulic sewerage dredger. A rectangular steel structure is formed by a first cross rod, a second cross rod, a longitudinal rod and a vertical edge of a crank arm, and the rectangular steel structure is fixed to a second stand column through the crank arm. The upper end of a drill rod penetrates through a first sleeve, the middle of the drill rod penetrates through a second sleeve, a drill bit is fixed to the lower end of the drill rod, the first sleeve is fixed to the first cross rod, the second sleeve is fixed to the second cross rod, a gear is fixed to the drill rod between the first sleeve and the second sleeve, the gear is a special-shaped gear with one toothed side and the other toothless side, a rectangular frame is arranged around the gear, gear racks are arranged on the two opposite edges of the rectangular frame respectively, the rectangular frame is fixed to the middle of a square rod, the left side of the square rod penetrates through a third sleeve, the right side of the square rod penetrates through a fourth sleeve, and the left end of the square rod is hinged to the right end of a transmission arm through a pin shaft.