The invention discloses a small cotton bag clamping mechanism. A small cotton bag conveying device comprises a hard conveying belt, multiple bag clamping mechanisms are arranged on the hard conveyingbelt side by side, each bag clamping mechanism comprises two supports, a fixing rod sleeves the top end of each support, a supporting plate is arranged at one end of each fixing rod and comprises a vertical plate and an oblique plate connected with the top of the vertical plate, and an obtuse angle is formed between each oblique plate and the corresponding vertical plate; a compression spring is arranged between each vertical plate and the corresponding support and sleeves the corresponding fixing rod, and a cotton bag clamp for clamping cotton bags is arranged on each notch. Through the smallcotton bag clamping mechanism, a cotton bag can be uniformly supported only through a U-shaped plate; a big cotton bag after being supported is uniform in wall and free of breakage, and efficiency and quality when compared with conventional artificial cotton bag supporting are improved greatly.