Synthesis of photo-thermal materials with high efficiency and anti-corrosion stability is the key for photo-thermal corrosive water evaporation, but remains a great challenge. Herein we for the first time develop mesoporous Fe3Si aerogel as a new photo-thermal material for remarkably efficient and stable corrosive water evaporation. The as-prepared Fe3Si aerogel has narrow mesopores with a size of 2-3 nm that can greatly reduce the thermal conductivity to 0.04 W·m−1·K−1  which is the lowest reported value so far, and depress the latent heat of water evaporation. The resulting Fe3Si aerogel supported on melamine foam represents outstanding seawater evaporation rate of 2.08 kg·m−2·h−1 and high solar-thermal utilization efficiency of 91.8% under one solar level irradiation, exceeding most of photo–thermal materials. Notably, owing to the strong corrosion resistance, the support-free hydrophobic Fe3Si aerogel displays utrastable solar-thermal water evaporation performance, with more than 1 kg·m-2·h-1 of water evaporation and outstanding cycling stability, in highly corrosive solutions of both 0.5 M H2SO4 and 1 M NaOH. Therefore, we believe that the Fe3Si aerogels have great potential for wide industrial applications such as seawater desalination, salt production, brine management and water purification.