Humidifying device for printing machine

The humidifying device comprises a humidifier, a connecting pipe and a humidifying pipe, a plurality of spraying holes are formed in the outer wall of the humidifying pipe, a sealing plate and an abutting assembly are arranged on the outer wall of the humidifying pipe, the two ends of the humidifying pipe are communicated with a blow-off pipe and a water inlet pipe respectively, and the two ends of the humidifying pipe are communicated with a water outlet pipe and a water outlet pipe respectively. And the connecting pipe, the blow-off pipe and the water inlet pipe are respectively provided with a first valve. In the using process of the printing roller, water mist in the humidifier is sprayed to the printing roller from the spraying holes, and therefore the situation that the printing roller is blurred in printing is reduced; and when the abutting assembly drives the sealing plate to seal the spraying hole, the water inlet pipe feeds water and flushes water scales in the humidifying pipe, and sewage with the