Abstract: Amorphous SiO₂ coating was prepared on the surface of carbon/carbon composites by low pressure chemical vapor deposition (LPCVD) with TEOS as precursor and N₂ as carrier gas. The effects of deposition temperature on the component, morphology and deposition rate of the coating were studied. The components and morphologies of the coatings were analyzed by XRD, XPS, FTIR, SEM and EDS, and the bioactivity of film was detected by the in vitro simulated body fluid (SBF) soaking. The results show that the main phase of the coating is amorphous SiO₂, and a thin layer of bone-like hydroxyapatite is deposited on the surface of the SiO₂ coating after soaking at 35 days which proves the coating has better bioactivity than that of the bare substrate. The deposition rate is increased with the development of temperature, and at the same time, the morphology of SiO₂ particles change from irregular to spherical and polygon shape finally.