Abstract: A limited space automatic loading and filling system for shells in submarines is designed to address the situation of limited space and insufficient manpower. The system uses a chain to drive the shells to a designated position, and then uses a two-stage projectile pushing mechanism to push the shells. It also uses a movable magazine slot to accommodate shells of different calibers. The device system is simple, does not affect the firing of shells, and saves time and labor. By using Solidworks software to establish a model and conducting strength verification analysis on its key components, it is proven that the automated filling system meets the design requirements.