The process model for BOF process can be applied to predict the liquid steel composition and bath temperature during the whole steelmaking process. On the basis of the traditional three-stage decarburization theory, the concept of mixing degree was put forward, which was used to indicate the effect of oxygen jet on decarburization. Furthermore, a more practical process model for BOF steelmaking was developed by analyzing the effect of silicon, manganese, oxygen injection rate, oxygen lance height, and bath temperature on decarburization.Process verification and end-point verification for the process model have been carried out, and the verification results show that the prediction accuracy of carbon content reaches 82.6% (the range of carbon content at the end-point is less than 0.1wt%) and 85.7% (the range of carbon content at end-point is 0.1wt%-0.7wt%) when the absolute error is less than 0.02wt% and 0.05wt%, respectively.