The invention relates to a shredding and rubbing device for a silage harvester. The shredding and rubbing device comprises a shredding mechanism and a rubbing mechanism. The rubbing mechanism comprises friction blocks, middle cushion blocks and a concave plate. The friction blocks are fixedly connected to the lower ends of movable cutter bases, and the middle cushion blocks are arranged between the friction blocks and the movable cutter bases. The friction blocks comprise the left thread friction blocks and the right thread friction blocks. The left thread friction blocks are D-type left thread rasp bar steel, and the right thread friction blocks are D-type right thread rasp bar steel. The left thread friction blocks and the right thread friction blocks are installed on the movable cutter bases on the left side and the movable cutter bases on the right side respectively in a staggered mode. The concave plate is fixedly connected to the lower end of a shredding cylinder shell, and gap adjustment bolts are arranged on the two sides of the concave plate. In the working process, crops are cut into sections through movable cutters and fixed cutters, the crops are changed to be in a shred shape under the rubbing function of the concave plate and the friction blocks after cut into the sections, and quality of silage is improved.