Abstract: Thermal control coatings serve as an important technology for spacecraft temperature management and regulation. The establishment of a multi-scale simulation framework allows for a deeper understanding of the physical and chemical properties of novel thermal control materials. A multi-scale design approach combining atomic and micro/nano scales has been developed in this study to investigate the optical absorption properties of La_0.75Sr_0.25MnO₃ (LSMO) thermal control coatings. Initially, first-principles calculations were employed to optimize the crystal structure of LSMO material and determine its critical optical constants. Subsequently, the finite-difference time-domain (FDTD) method was used to simulate the optical absorption characteristics of LSMO coatings at various thicknesses. The results demonstrate that LSMO coatings exhibit high-efficiency optical absorption across the solar spectrum, and the absorption efficiency reaches a steady state when coating thicknesses exceed 1 μm. The simulation methods used in this study provide theoretical support for revealing the optical properties of novel lanthanum strontium manganese oxide coatings, and offer a reference for the design and application development of thermal control coatings for spacecraft.