With　the　advantages　of　high　strength　and　high　temperature　resistance,　C/SiC　composites　have　been　widely　used　in　aerospace　field.　In　this　paper,　the　oxidative　ablation　in　C/SiC　composites　is　studied　experimentally　and　simulatively.　Therefore,　oxidation　kinetics　mechanism　of　carbon　fiber　is　researched　by　both　simulation　and　experimental　in　this　article.　Firstly,　the　oxidation　weight　loss　rate　of　carbon　fiber　at　different　temperature　and　oxygen　partial　pressure　is　measured　experimentally,　and　the　calculation　relation　is　fitted.　Secondly,　based　on　calculation　relation　and　lattice　Boltzmann　method　(LBM),　the　oxidation　ablation　model　of　carbon　fiber　is　established.　Finally,　the　oxidation　ablation　characteristics　of　C/SiC　composites　are　simulated.　The　results　show　that　with　the　increase　of　temperature,　the　controlling　factor　of　ablation　rate　will　gradually　change　from　the　chemical　reaction　rate　to　the　diffusion　rate　of　gas.　The　ablation　rate　of　pure　carbon　fiber　is　about　3-27　times　that　of　carbon　fiber　in　C/SiC　composites,　and　the　higher　the　temperature,　the　greater　the　difference　is.　This　study　provides　a　theoretical　basis　for　improving　the　oxidation　resistance　of　C/SiC　composites　under　high　temperature　oxygen　atmosphere.　©　2022,　Science　Press.　All　right　reserved.