A banknote receiving device, comprising: a supporting frame, configured to mount subsequent components, the supporting frame comprising two lateral plates having the same structure, each of the lateral plates being provided with a hole, wherein a shape of the hole is such that a rotating shaft is floatable up and down in the hole; a pair of roller wheels, located at an inlet of the banknote receiving device and configured to bring in banknotes by clamping; a blade wheel, mounted on the supporting frame via the rotating shaft, the blade wheel being joined with the pair of roller wheels and configured to convey the banknotes delivered from the pair of roller wheels in a way of carrying the banknotes and rotating; and a support plate, located below the blade wheel, configured to carry the banknotes delivered from the blade wheel, the support plate being movable up and down under the action of a transmission mechanism to adjust a size of a banknote receiving space; wherein the banknote receiving device further comprises a blade wheel floating control device configured to control an upward and downward floating of the blade wheel and to further control the support plate to move downward according to an upward floating degree of the blade wheel to increase the banknote receiving space, wherein two ends of the rotating shaft are respectively mounted in the holes of the two lateral plates via respective bearings; and the blade wheel floating control device further comprises: a coded disc, which is fixed on the rotating shaft, is rotatable synchronously with the blade wheel and floatable up and down with the blade wheel; a sensor, fixed above the coded disc, wherein the coded disc is configured to optionally block a light-transmittable point of the sensor when the coded disc floats up and down with the blade wheel, to allow the sensor to sense the upward floating degree of the blade wheel; and a pair of tension springs arranged symmetrically, each of the tension springs having an upper end fixed on the respective bearing of the rotating shaft and a lower end fixed on the respective lateral plate of the supporting frame. a supporting frame, configured to mount subsequent components, the supporting frame comprising two lateral plates having the same structure, each of the lateral plates being provided with a hole, wherein a shape of the hole is such that a rotating shaft is floatable up and down in the hole; a pair of roller wheels, located at an inlet of the banknote receiving device and configured to bring in banknotes by clamping; a blade wheel, mounted on the supporting frame via the rotating shaft, the blade wheel being joined with the pair of roller wheels and configured to convey the banknotes delivered from the pair of roller wheels in a way of carrying the banknotes and rotating; and a support plate, located below the blade wheel, configured to carry the banknotes delivered from the blade wheel, the support plate being movable up and down under the action of a transmission mechanism to adjust a size of a banknote receiving space; wherein the banknote receiving device further comprises a blade wheel floating control device configured to control an upward and downward floating of the blade wheel and to further control the support plate to move downward according to an upward floating degree of the blade wheel to increase the banknote receiving space, wherein two ends of the rotating shaft are respectively mounted in the holes of the two lateral plates via respective bearings; and a coded disc, which is fixed on the rotating shaft, is rotatable synchronously with the blade wheel and floatable up and down with the blade wheel; a sensor, fixed above the coded disc, wherein the coded disc is configured to optionally block a light-transmittable point of the sensor when the coded disc floats up and down with the blade wheel, to allow the sensor to sense the upward floating degree of the blade wheel; and a pair of tension springs arranged symmetrically, each of the tension springs having an upper end fixed on the respective bearing of the rotating shaft and a lower end fixed on the respective lateral plate of the supporting frame.