Novel high-temperature thermal insulation materials (i.e., ceramic fiber insulation materials and aerogels) become research hotspots due to their low density, low thermal conductivity, and superior thermal insulation properties. Ceramic thermal insulation materials can be classified into two categories, i.e., rigid ceramic thermal insulation tiles and flexible ceramic fiber thermal insulation blankets. Ceramic thermal insulation materials serve as one of the primary thermal protection materials on the surfaces of aerospace equipment due to their superior characteristics such as porosity, low thermal conductivity, high-temperature stability, and excellent mechanical properties. Aerogel is a lightweight material with a nano-porous structure. At atmospheric pressure, silica aerogel has the lowest thermal conductivity among any other insulators. In various applications, aerogel increasingly replaces more conventional materials. The skeleton and porous morphology of aerogel can be controlled in a nanoscale to provide various remarkable physical properties, such as ultra-low density, intense adsorption capacity, ultrahigh specific surface area, and ultralow thermal conductivity.However, the most existing thermal insulation materials are generally isotropic and hydrophilic, significantly limiting their applications in humid environments. The widely used high-temperature thermal insulation materials are typically porous structures, and their nanopores and high specific surface areas contribute to reducing thermal conductivity through a gas-phase heat transfer, thus having superior thermal insulation performance. Nevertheless, their thermal conductivity increases, and this trend intensifies with increasing ambient humidity when porous materials absorb moisture in humid environments, leading to a degraded thermal insulation performance. Moreover, in a direct contact with water, the nanoporous structure of the materials can collapse under capillary forces, causing a significant increase in thermal conductivity.This review comprehensively represents the implementation methods and performance aspects of water resistance for three commonly used high-temperature thermal insulation materials, i.e., ceramic fiber thermal insulation tiles, ceramic fiber thermal insulation blankets, and silica aerogel. The ceramic fiber thermal insulation tiles enhance their high-temperature stability and water resistance through the application of high-emissivity coatings. The ceramic fiber thermal insulation blankets achieve a water resistance via electrostatic spinning and surface modification techniques. For silica aerogel thermal insulation materials, their water resistance is improved via modifying their surfaces with organic hydrophobic groups and adopting hydrothermal-assisted drying methods. This review also identifies some challenges for the improvement of the existing materials and provides an outlook on the future development directions.Summary and ProspectsThis review represents the research advancements in high-temperature insulation materials (i.e., water-resistant ceramic fiber insulation tiles, insulation blankets, and aerogels). Some strategies for enhancing their water resistance, such as the application of high-emissivity coatings, chemical vapor deposition, and modification with organic hydrophobic groups, are described. These materials possess a significant application potential at multiple fields due to their low density, robust water resistance, and efficient thermal insulation properties. Nevertheless, some challenges persist in maintaining water resistance at high temperatures, simplifying manufacturing processes, and developing novel materials. A future research should prioritize enhancing the water resistance of materials at elevated temperatures, streamlining production processes, and innovating novel materials. In addition, the stability and durability of these materials in practical applications also need to be further investigated to facilitate the technological advancements and industrial upgrading.