In a high-temperature and dry oxygen environment， SiC materials will be oxidized to form SiO₂ oxide layer， which affects the material performance. The growth of SiO₂ on SiC is controlled by the diffusion of oxygen through the oxide layer. Due to the limitation of temperature conditions， it is not easy to measure the oxygen diffusion in high-temperature oxide with traditional experimental methods. Molecular dynamics（MD） simulation is used to study the diffusion behavior of oxygen in molten SiO₂ at different temperatures. Based on the potential functions， such as Morse， L-J， etc， and their parameters， the amorphous SiO₂ structure at high temperature is simulated. The mean square displacement （MSD）curves and diffusion coefficients of oxygen at 950， 1 100， 1 200， 1 300 and 1 400 ℃ are calculated. The effect of temperature on gas diffusion is analyzed by fitting the Arrhenius function. Through this study， it is expected to provide a reference to the oxidation behaviors of SiC-based ceramics and composites.