The invention discloses a paper money detection device comprising a paper money conveying belt, a fixed rack base plate, a sensor fixed rack, a first photoelectric sensor, a second photoelectric sensor, a third photoelectric sensor and a control module. According to the detection device, the three fixed photovoltaic sensors are used for measuring time of shielding the three photovoltaic sensors by paper money so as to calculate the length of the paper money and determine the denomination of the paper money, so that low-cost, rapid and accurate paper money denomination detection can be realized. The detection device has advantages of simple mechanical structure and low manufacturing cost; and paper money denomination identification and worn paper money detection can be realized.