SiO2 aerogel has poor mechanical properties and strong thermal insulation properties. In order to make SiO2 aerogel a good thermal insulation material, a preparation method of SiO2 aerogel fiber thermal insulation composites was proposed. SiO2 aerogel fiber insulation composites were prepared under atmospheric pressure condition by ethyl orthosilicate (TEOS) as precursor, glass fiber and ceramic fiber as reinforcers, and silane coupling agents KH550 and KH570 as fiber treatment agents, and the material properties were characterized. The results show that the higher the content of hexadecyl trimenthyl ammonium (CTAB) in precursor is, the lower the thermal conductivity of SiO2 aerogel in composite is, which can be as low as 0.028 W/(m·K). When using silane coupling agent KH550, the interface bonding strength between matrix and fiber is higher. The mechanical properties of SiO2 aerogel reach a high level with the addition of fiber. When the molar ratio of TEOS to CTAB is 1∶0.022, the thermal conductivity of glass fiber/SiO2 aerogel composites treated with KH550 is 0.054 W/(m·K), the mechanical properties are good, and the thermal insulation property is optimal.