Flat-sheet ink-jet printer capable of ensuring flatness of paper

The invention discloses a flat-sheet ink-jet printer capable of ensuring the flatness of paper, which comprises an ink-jet printer body, and the ink-jet printer body is provided with a feeder area, a pull gauge area, an ink-jet area, a drying area, a waste kicking area and a paper collecting area, and is characterized in that the feeder area, the pull gauge area, the ink-jet area and the paper collecting area are arranged at the joint of the pull gauge area and the ink-jet area; humidifying mechanisms are arranged at the joint between the code spraying area and the drying area and the joint between the code spraying area and the drying area respectively, each humidifying mechanism comprises a humidifying pipeline, a plurality of steam spraying holes distributed at equal intervals are formed in the top end face of each humidifying pipeline, drainage holes are further formed in the bottom end faces of the two ends of each humidifying pipeline, one end of each humidifying pipeline is closed, and the other end of