Abstract: A carbon-oxygen reaction model was developed to simulate actual reactions in the RH process, and the calculation results were in good agreement with the measurement results. It was found that the initial carbon content had no influence on the carbon content at the end of decarburization in RH. The carbon-oxygen reaction nearly reached equilibrium due to 14 minutes' reaction at a decarburization rate of less than 1.5×10^-6 min^-1. The ratio of ΔO/ΔC of decarburization in the RH process decreased with the increase in the TFe content of ladle slag, and the ratio was near the theory ratio when the TFe content was 8%.