Abstract: Against the backdrop of rapid development of new power systems and increasing load, enhancing the fire protection capability of substations (converter stations) has become crucial for ensuring the safety of energy facilities. The thermal stability and flame retardancy of fireproof sealing materials directly impact the safe and reliable operation of power equipment. Focusing on current issues such as unclear composition-property relationships and insufficient evaluation of engineering applicability, this study systematically investigates the multi-scale performance of four typical types of products, including silicone-based (1#, 3#) and acrylic-based (2#, 4#) materials, both domestically and internationally. Through comprehensive evaluation combining microstructural characterization with tests on thermal, fire resistance, and mechanical properties, the coupling relationship between material composition and performance is revealed. The results show that the domestic silicone-based material 3# exhibits the best overall performance due to its high content of compounded inorganic fillers (Al₂O₃、TiO₂、ZnO) and an organic-inorganic interpenetrating structure, with a char residue of 50.9%, limiting oxygen index of 48%, tensile strength of 1.80 MPa, and zero shrinkage, meeting the UL-94 V-0 flame retardancy requirement. The foreign silicone-based material 1# has a high initial pyrolysis temperature (363.7℃) but its mechanical performance is 31.2% lower than that of 3#, with insufficient fire resistance. The acrylic-based materials 2# and 4# exhibit poor thermal stability, with initial thermal degradation temperatures of 276.7℃ and 177.2℃, respectively. Material 2# is flammable (LOI ~22%), while material 4#, although having better fire resistance (LOI ~36%), contains excessive As element (22.6 ppm) and exhibits significant shrinkage, limiting its engineering application. In summary, the domestic silicone-based material 3# demonstrates the best overall performance and can meet the engineering application requirements of State Grid power equipment. This study is expected to provide a scientific basis for the selection of fireproof materials in power equipment, offering significant engineering value.