The invention belongs to the field of sewage treatment, and discloses a grille decontamination system. The system comprises an outer grille frame, wherein a rotation unit is arranged in the outer grille frame, and a plurality of mesh plates used for filtering impurities out of sewage are uniformly distributed on the rotation unit; and the outer grille frame is connected with a cleaning unit used for clearing impurities adhered to the mesh plates, as well as a first slag removal unit and a second slag removal unit which are used for collecting the impurities. By means of the cleaning unit and the slag removal units, the problem that the impurities are taken back is solved, and the treatment efficiency is high; and treated impurities contain little water, are not required to be squeezed and can be directly collected.