Printed matter quality on-line monitoring device

The utility model discloses a presswork quality on-line monitoring device which comprises a monitoring device body, the outer wall of the monitoring device body is provided with a roller used for fixing presswork, the outer wall of the roller is provided with a protection assembly used for protecting the presswork, the protection assembly comprises a protection cover, and the inner wall of the protection cover is provided with a connecting rod. A connecting rod is fixedly connected to the inner wall of the protective cover, a roller is arranged at the end of the connecting rod, fixing blocks are symmetrically arranged on the outer wall of the protective cover, threaded grooves are formed in the connecting positions of the fixing blocks and the monitoring device body, and bolts are connected into the threaded grooves in a threaded and penetrating mode. The end of the connecting rod is rotationally connected with a roller, and the protective cover is designed to protect the outer wall of the printing product, s