The control fin is a key component in a guided missile's propulsion system, stabilizing the missile's attitude and maintaining its flight trajectory under high-speed conditions. Such components demand high mechanical strength and thermal stability. However, traditional control fin designs have primarily focused on external geometry, overlooking opportunities to enhance performance through internal structural design.To address this limitation, this study proposes a design approach that integrates lattice structures within the control fin using metal additive manufacturing. A body-centered cubic (BCC) lattice was selected, with strut diameter and unit cell aspect ratio defined as the primary design variables. Finite element analysis in Abaqus was used to evaluate structural behavior, analyzing stress and displacement distributions based on variations in these lattice parameters. Manufacturability and lightweight characteristics were also assessed. Results indicate that increasing the strut diameter improves structural stability, with stress predominantly concentrated near lattice joints. Building on these findings, a non-uniform lattice design, derived from the uniform lattice analysis, was applied, demonstrating improved stress distribution and overall structural performance. This approach shows that lattice-based internal structures, enabled by metal additive manufacturing, can significantly enhance the structural performance of guided missile control fins while achieving substantial weight reduction.