Metal foreign objects left in fields pose a significant challenge during silage harvester operation, leading to reduced mechanical efficiency, compromised feed quality, and risks to livestock safety. However, due to the complex and demanding working environment of agricultural machinery, such as high levels of vibration, dust, and temperature/humidity fluctuations, and the minimal dimensions of critical metallic foreign objects, which often require detection down to a few millimeters, the application of traditional metal detection technology faces significant technical challenges in this field. As a result, metal detection devices have not yet become standard equipment on silage harvesters in China. By consulting the relevant literature, this paper systematically analyzes the basic principles of metal detection technology, compares the technical characteristics of metal detection devices in the field of agricultural machinery and equipment at home and abroad, and puts forward suggestions for the challenges of reliability, foreign object removal, and system response time of metal detection devices. The application of metal detection technology in the field of agricultural machinery and equipment provides information support.