The present invention discloses a banknote serial number identification device which comprises a contact image sensor which is used for collecting banknote image data through a transmission imaging mode, a group of white light transmission light sources and a group of infrared transmission light sources which are arranged in front of the contact image sensor and alternatively provide light sources for the contact image sensor to collect banknote image data, and an image collection processing plate which is connected to the contact image sensor through a data line and is integrated with a field programmable gate array and an RISC microprocessor. The field programmable gate array is used for controlling the on and off of the white light transmission light sources and the infrared transmission light sources and controlling the contact image sensor to obtain the banknote image data and then transmitting the collected banknote image data to the RISC microprocessor for storage. According to the device and the method, the identification accuracy can be improved, the design of a hardware circuit is simplified, the production assembly process is improved, and the cost of a currency detector is reduced.