An image scanning device, comprising: a bearing member, configured to receive paper bills; a light source; a lens, wherein incidence side of the lens and the bearing member are correspondingly arranged and the lens is configured to receive reflected light or transmission light of the paper bills under the irradiation of the light source and receive emitted light of the light source; a first converter, arranged on emergent side of the lens and configured to convert light signals from the lens into electric signals; wherein the image scanning device further comprises: a controller, connected with the light source and the first converter, and configured to control the light emitting time of the light source, acquire electric signals during the light emitting process of the light source, and acquire the electric signals again after the light source stops emitting light for a preset period of time, wherein the light source includes ultraviolet light, the ultraviolet light excites secondary light of the paper bills, and wherein the controller is further configured to sample the lights of other colors at an interval of N lines after sampling the secondary light, N being a number greater than 1, wherein the light source comprises: a first light source, arranged at a first side of the bearing member, and the first light source is a transmission light source, the paper bills generate transmission light when irradiated by the transmission light source; and a second light source, arranged at a second side of the bearing member, is a reflection light source configured to generate ultraviolet light, the paper bills generate reflected light when irradiated by the reflection light source; and the second side is a side opposite to the first side. a bearing member, configured to receive paper bills; a light source; a lens, wherein incidence side of the lens and the bearing member are correspondingly arranged and the lens is configured to receive reflected light or transmission light of the paper bills under the irradiation of the light source and receive emitted light of the light source; a first converter, arranged on emergent side of the lens and configured to convert light signals from the lens into electric signals; wherein the image scanning device further comprises: a controller, connected with the light source and the first converter, and configured to control the light emitting time of the light source, acquire electric signals during the light emitting process of the light source, and acquire the electric signals again after the light source stops emitting light for a preset period of time, wherein the light source includes ultraviolet light, the ultraviolet light excites secondary light of the paper bills, and wherein the controller is further configured to sample the lights of other colors at an interval of N lines after sampling the secondary light, N being a number greater than 1, wherein the light source comprises: a first light source, arranged at a first side of the bearing member, and the first light source is a transmission light source, the paper bills generate transmission light when irradiated by the transmission light source; and a second light source, arranged at a second side of the bearing member, is a reflection light source configured to generate ultraviolet light, the paper bills generate reflected light when irradiated by the reflection light source; and the second side is a side opposite to the first side. a controller, connected with the light source and the first converter, and configured to control the light emitting time of the light source, acquire electric signals during the light emitting process of the light source, and acquire the electric signals again after the light source stops emitting light for a preset period of time, wherein the light source includes ultraviolet light, the ultraviolet light excites secondary light of the paper bills, and wherein the controller is further configured to sample the lights of other colors at an interval of N lines after sampling the secondary light, N being a number greater than 1, wherein the light source comprises: a first light source, arranged at a first side of the bearing member, and the first light source is a transmission light source, the paper bills generate transmission light when irradiated by the transmission light source; and a second light source, arranged at a second side of the bearing member, is a reflection light source configured to generate ultraviolet light, the paper bills generate reflected light when irradiated by the reflection light source; and the second side is a side opposite to the first side. a first light source, arranged at a first side of the bearing member, and the first light source is a transmission light source, the paper bills generate transmission light when irradiated by the transmission light source; and a second light source, arranged at a second side of the bearing member, is a reflection light source configured to generate ultraviolet light, the paper bills generate reflected light when irradiated by the reflection light source; and the second side is a side opposite to the first side.