In order to improve the propellant weighing precision and production efficiency, the continuous weighing processes of 26, 16 and 5 mm diameters propellant were dynamically simulated by 3-stage charging mode and Rocky discrete element software, the work load of the discharge plate of the weighing hopper is determined. Based on the Ansys Workbench finite element software, the stress and deformation of the weighing hopper are simulated to determine whether the material is leaking or not, and the unloading time is obtained. The results of dynamic simulation show that the structure design of weighing device can meet the requirement of loading 80 kg, no material leakage will occur, and the visualization of weighing process can be realized, which can accurately reflect the actual weighing and packing conditions. It is the instructive experience for the accurate control of the weighting and packing process.