Aiming at the requirements of micro amount medicament accuracy of weighting device in certain type grain pressing device, introduce a micro amount medicament weighting technology which combined linear vibration feeder with servo spiral feeding. Describe the component of mechanical structure and control system of certain type auto grain pressing device. Emphasis on structure design feature of spiral feeding, close loop weighting technology and initial lead forecasting technology, acquire application results and carry out analyzing. The application results show: the micro amount medicament weighting technology can ensure accuracy of weighing in ±1 mg, meet equipment weighing requirements, and has a high degree of automation, safe and reliable, and the advantages of convenient operation, can be applied in other similar weighing equipment.