A system simulation mathematical model on oxygen blast furnace ironmaking process is established. Provided that the material composition and the values of necessary process parameters are given, the model can predict the consumptions of raw material, fuel and flux, the quantity and composition of slag, the quantities and components of all kinds of gases, etc. At the condition of 90% stack ore metallization, the calculated results of the model show that when more circulating gas are introduced into the stack, the heat controls the total gas for the stack ore reduction, while when more circulating gas are introduced into the hearth, the reductive components control the total gas for the stack ore reduction. At normal operations with coke rate fixed, the coal consumption linearly increases with the output top gas. When the coke rate is fixed at 200 kg, the minimum value of calculated coal rate is 200 kg or so.