Abstract: Based on the mechanism that the oxidation rate of carbon is primarily related to oxygen supply in the earlier stage and mass transfer of carbon in molten steel in the later stage,a mathematical model was proposed to describe the argon oxygen decarburization(AOD) oxidation refining process of low carbon twinning induced plasticity(TWIP) steel. The variations of C,Si and Mn contents in molten steel in an 8 t AOD converter during the oxidation refining process were analyzed by this model. The result shows that the error of the calculated carbon content is less than 5% compared with the measured values. It is also found that the critical carbon content of decarburization of the TWIP steel in the 8 t AOD converter is between 0.33% and 0.38%.