The invention discloses a residue-holding float bowl structure for a drainage system. The structure comprises a tank body, wherein a cylindrical float bowl is arranged in the tank body and is in a hollow shape, two end planes of the tank body are sealed, and the float bowl is flatly placed to be vertical to a water current direction and the length of the float bowl stretches across the two side walls of the tank body, and rotary arms are fixedly connected on the two end planes of the float bowl and are respectively hinged onto the side walls of the tank body. When the float bowl structure is adopted to hold residues, a part of the hollow float bowl is immersed below the water surface, and the other part of the hollow float bowl floats above the water surface, and floating objects are blocked through the float bowl when the water flows through the float barrel, and the water discharges from the bottom of the float bowl, so that the structure solves the problem that a filter screen can be easily blocked in the prior art, and the residue-holding equipment are not needed to wash and maintain; furthermore, the size range of the floating residues held up by the floater structure is larger, the floating residues are held up more thoroughly, so that the residue-holding effect can be improved; in addition, the residue-holding can be automatically controlled through hydraulic power, and the float bowl structure is simple in structure, convenient to install, good in technology, and safe and reliable to use.