A guided missile is a weapon system used in the interception of a ballistic missile using kinetic energy of a kill vehicle. The DACS (Divert and Attitude Control System) is a quick reaction propulsion system and subsystem of a kill vehicle that provides control over positions of a kill vehicle. The DACS allows for the interception of its target with greater accuracy and reliability. A Kill vehicle needs to move at high speed in a bid to intercept a ballistic missile after detecting a target. Thus, the weight reduction design of DACs system is required. The DACS operates under high temperature and pressure environment. In this study, one-way FSI (Fluid and Structure Interaction) analysis were conducted for various types of weight reduction valve model to validate its robustness. Through this process, we suggest an optimized weight reduction valve model