Porous crack-free C/SiO2/SiC ternary composite aerogel monolith was prepared by the one-pot sol-gel method using Catechol/formaldehyde (CF) and 3-aminopropyltriethoxysilane as the organic and inorganic precursors.It was derived from the Catechol/formaldehyde/silica (CF/SiO2) aerogel via CO2 supercritical drying, followed by subsequent carbonization (800 ℃/3h) and carbothermal reduction (1300 ℃, 1400℃ and 1500℃).The evolution of physical properties, crystal structure, morphology and pore structures from CF/SiO2 to C/SiO2/SiC aerogel was investigated by different methods.XRD and XPS techniques both revealed that SiCphase began to emerge when heat treatment reached up to 1400 ℃, and it became obvious at 1500 ℃.The bulk densities of CF/SiO2, C/SiO2 and 1400 and 1500-C/SiO2/SiCcomposite aerogel were 0.231 g/cm3, 0.226 g/cm3, 0.329 g/cm3 and 0.249 g/cm3, respectively, with the corresponding mass loss of 49.4%, 18.0 % and 21.2 %.The network structures become more homogeneous after carbothermal reduction, and SiO2 phase and SiC phase existed as particles and nanowires.The specific surface areas of CF/SiO2, C/SiO2,1400 and 1500-C/SiO2/SiC are 170.67 g/m2, 261.97 g/m2, 523.64 g/m2 and 746.87 g/m2, respectively.Carbothermal reduction mechanism was also discussed in this article based on the experiment and characterization results.