The invention discloses a blocking device for assisting in maintaining of a water conveying pipeline. The device comprises a fixed plate, a first side plate is arranged on one side of the fixed plate, a second side plate is arranged on the other side of the fixed plate, a first guide pipe is arranged on one side of the first side plate, a first fixed disc is arranged between the first guide pipe and the first side plate, the first fixed disc is arranged on the outer side of the first side plate, a first guide cylinder is arranged on one side of the second side plate, a first fixed ring is arranged between the first guide cylinder and the second side plate, the first fixed ring is arranged on the outer side of the second side plate, the position between the first guide pipe and the first guide cylinder is sleeved with a first moving shaft, a blockage plate is arranged above the fixed plate, a rubber seal plate is arranged on the front face of the blockage plate, one end of the first moving shaft is arranged on one side of the back face of the blockage plate, a hydraulic cylinder is arranged on the fixed plate, a piston rod is arranged on the front of the hydraulic cylinder, and the end of the piston rod is arranged in the middle of the back face of the blockage plate. A draining opening of the water conveying pipeline can be closed and controlled.