Grab cleaner is mainly composed of hoisting mechanism, wire rope, rake bucket, wire rope pulley, rake bucket tensioning device, mechanical over-moment protection, mobile driving, ground fixed track and mobile driving positioning device. The positioning and cleaning action of the whole machine, the lifting and lifting of the rake bucket, the opening and closing of the rake bucket, and the scraping of the rake dirt are the same as the fixed installation of the wire rope traction rake bucket grille cleaner. Only the upper frame and the lower frame are separated, and the upper frame are all installed on the mobile traveling car. Its working principle is: when removing pollution, the rack moves to the grille position which needs to be cleaned up. When the upper and lower racks are aligned accurately, the rake bucket can be smoothly lowered to remove pollution. For the wide grille, the decontaminator moves the effective width of a tooth rake after decontamination, and continues to decontaminate until the grille surface is finished and the water level difference before and after the grille reaches the normal value. For multi-channel distribution grids, the decontaminator moves to another channel after the grille of one channel has been decontaminated, and continues to decontaminate until the grille surface of all channels has been decontaminated and the water level difference before and after the grille reaches the normal value.