The invention discloses a banknote bundling, gear regulating and back preventing device. The device comprises a banknote bundling machine body, a regulating shaft, a regulating rack and a gear regulating mechanism, wherein the regulating shaft and the regulating rack are arranged in the banknote bundling machine body; the gear regulating mechanism is used for regulating the placement depth of thebanknote; one end of the regulating shaft is provided with a regulating button and a regulating gear which is engaged with the regulating rack is fixed at the other end of the regulating shaft; and the gear regulating mechanism is arranged at the middle end of the regulating shaft. In the device, the gear regulating mechanism is controlled by manually rotating the regulating button so that the placement depth of the banknote is regulated; a paper tape is bundled at the different positions of the banknote so that the requirement on bundling of various currency sorts of RMB is met; and the other end of the regulating shaft is provided with a regulating spring which makes a marble head on a regulation gear return to a hole position on a regulation gear frame so as to play a back preventing role. The device has the advantages of simple and clear structure, small volume, high work efficiency and convenient operation and maintenance, thereby meeting the requirement on finance office automation, security and portability.