SiOC aerogels with different C/Si ratio were prepared by sol-gel method with ethyl orthosilicate (TEOS) and methyl trimethoxysilane (MTMS) as precursor. Then the SiOC aerosol was sprayed on the flexible ceramic fiber insulation blanket by atmospheric spraying, therewith, the SiOC aerogel/flexible ceramic fiber composite material was successfully prepared. The C/Si ratio is an important factor affecting the performance of SiOC aerogel/flexible ceramic fiber composites. As the ratio of C/Si (atomic ratio) increases, the gel time of SiOC sol is prolonged, whilst it is easier to infiltrate into the insulation blanket; the density and thermal conductivity of the composite decrease first and then increase. When the ratio is 0.67 the thermal conductivity of the composite is the lowest, namely, 0.026 W/m·K at room temperature and 0.174 W/m·K at 1000℃ respectively. Compared with unmodified insulation blanket the thermal conductivity is significantly reduced, especially by 47% at high temperature environment. The composite has excellent high temperature resistance and oxidation resistance. At 1200℃ in air the mass loss percentage of the sample is about 1% after pyrolysising for 1 h, whilst about 5% after pyrolysising for 3 h. As the C/Si ratio increases the mass loss of the composite increasees; in addition, the SiOC aerogel composite material also has good hydrophobic properties, flexibility and resilience.