Adaptive Optics (AO) is a widely used technique for correcting wavefront errors caused by atmospheric turbulence, in various optical systems [1]. As a core component of AO, the Deformable Mirror (DM) compensates for these errors by physically altering its reflective surface to restore the quality of the incoming wavefront. With the recent expansion of research and applications for High-Energy Laser (HEL) weapon systems, the role of AO in preventing beam focus degradation has become increasingly critical, especially as the distance to the target increases. Unlike AO systems for low-energy applications, such as astronomical observations, DMs in HEL systems require a cooling system to suppress thermal deformation induced by intense laser irradiation [2]. This work presents the design and optimization process of an actively cooled DM utilizing a liquid coolant. The coolant inlet/outlet positions and internal flow path geometry were optimized using commercial simulation tools, Ansys Fluent and Ansys Mechanical (Ansys Inc.), to minimize surface distortion during laser operation. Through numerical analysis, the temperature distribution and structural deformation of the mirror surface were evaluated. The results confirmed that both thermal and structural responses remain within the target design tolerances, thereby verifying the effectiveness of the proposed cooling system.