Abstract: The rock wool fiber reinforced SiO₂ aerogel composite thermal insulation material was subjected to accelerated aging tests for different times (1-15 d) at 600 ℃. The microstructure, compression performance and thermal conduction performance were studied after aging. The results show that with increasing aging time, the aerogel filled in the rock wool fiber grid space agglomerated, and the fracture degree of fiber increased. When the aging time was 15 d, the aerogel was in a sintered state, and the structure was dense. The stress of the unaged sample changed linearly with strain. The stress of the aged sample increased faster than that of the unaged sample. The stress increased fastest with strain when the aging time was 15 d. With increasing aging time, the heat transfer path of the sample became shorter, and the thermal conductivity coefficient increased.