The invention discloses a stained paper printer conveying mechanism. The stained paper printer conveying mechanism comprises a support, a drive roller, a driven roller and a conveying part. The drive roller and the driven roller are arranged at the two ends of the support correspondingly. The conveying part surrounds the drive roller and the driven roller, and one conveying direction is achieved. The stained paper printer conveying mechanism further comprises two or more support plates and movable supporting devices. The positions, corresponding to the conveying part, of the support plates are provided with notches with upward openings. The support plates are embedded in the conveying part through the notches, the tops of the support plates are arranged below the conveying part, a protruding part is arranged at the front end of each support plate, and the top ends of the protruding parts are arranged above the conveying part. The movable supporting devices are arranged on the two sides of the conveying mechanism and used for conducting supporting and making the support plates move in the conveying direction and the height direction. The conveying part is a conveying belt. The drive roller and the driven roller are provided with synchronous wheels, and the support plates are connected with a negative pressure mechanism.