The invention provides a humidifying mechanism of a printing device for printed fabric and belongs to the technical field of machines. The humidifying mechanism of the printing device for the printed fabric solves the problem that an existing printing device consumes a large amount of water. The printing device for the printed fabric comprises a humidifying dust collection chamber and a first fabric guide roller which is horizontally arranged in the humidifying dust collection chamber. The humidifying mechanism comprises a water pump arranged at the bottom of the humidifying dust collection chamber. The first fabric guide roller is hollow, and one end of the first fabric guide roller is closed. The side wall of the first fabric guide roller is provided with multiple water spraying holes. A water discharging pipe is inserted into the other end of the first fabric guide roller. The outer end of the water discharging pipe extends out of the first fabric guide roller and communicates with an outlet of the water pump. A water storage tank is further arranged in the humidifying dusts collection chamber. An opening of the water storage tank is opposite to the first fabric guide roller. A water discharging opening is formed in the bottom of the water storage tank. An inlet of the water pump is connected with a water inlet pipe. The water inlet pipe is a t-branch pipe. The water inlet pipe is provided with two water inlet ends and a water outlet end. The water outlet end communicates with the inlet of the water pump. One water inlet end communicates with the water discharging opening. The humidifying mechanism of the printing device for the printed fabric has the advantage of being small in water consumption.