The application provides a mobile metal monitoring device, which belongs to the technical field of environmental monitoring. The device includes: an aircraft, a sampling component, a sample preparation component and a detection mechanism. The aircraft has an airtight cabin. The sampling components include a sampling tube and a piston, and the sampling tube is vertically installed at the bottom of the aircraft. The sample preparation components include a filter bucket and a pressure plate. There are multiple one-way valve holes on the bottom of the filter bucket. The bottom of the filter bucket is located outside the aircraft. The pressure plate slides inside the filter bucket. There is a ring at the bottom of the pressure plate for storing sediment. The sample piece, the filter bucket and the sampling tube are connected through a connecting tube, and the sample preparation components are arranged in multiple positions along the circumference array of the sampling tube. The detection mechanism includes a spectrometer, which is used to detect the sample piece on the bottom surface of the pressing plate, and the spectrometer moves along a circle and is arranged outside the sample preparation part. Multiple samples can be collected, sample prepared and pre-inspected, and more representative sediment samples can be obtained more conveniently and quickly.