With the logistics industry's demand for flexibility and efficiency in storage systems, modular design has become an important direction in the development of storage systems. Based on the dovetail groove and pin dual connection structure of the main frame, combined with the linear slide design of the inner frame, this paper proposes a modular storage system structure. The main frame has a dovetail groove structure on all four sides, allowing modules to be seamlessly joined in three dimensions, effectively improving space utilization. The pin structure provides double fixation by rotation locking, increasing the stability of the connection. A linear slide on the inner frame provides precise control of pallet movement and simplifies access to items. The system is modelled using SolidWorks and the mechanical simulation of key components is completed using AYSNS software. The experimental results show that the system performs well in terms of structural strength, operational accuracy and connection reliability, which provides a new idea for the structural design of the modular storage system.