Due to the continuous improvement of digital imaging technology, making counterfeit banknotes has become easier and cheaper. In order to solve the problem of counterfeit banknotes, the main purpose of this article is to develop a banknote detection system (BDS). This system will detect whether banknotes are included in the digital image during scanning or printing, reducing the use of high-resolution digital imaging products for counterfeit banknote manufacturing opportunity. The system is divided into three main steps: magnetic detection, fluorescent detection and watermark detection. In the future, this system can be implanted in image-related computer peripherals (such as scanners, printers or multi-function printers) to scan banknotes at the beginning or prevent blockages when copying banknotes.