Abstract: The steelmaking process involves a series of operations, including decarburization, desulfurization, dephosphorization, and deoxygenation. Therefore, this process is controlled by complex multifactors such as high and inhomogeneous reactor temperatures, simultaneous multiphase chemical reactions, and mutual coupling between phases in terms of mass, momentum, and heat transfer. Accurate prediction and control of the steelmaking process has always been a difficult problem in the ironmaking and steelmaking industries and a popular topic in metallurgy. The reaction thermodynamics and kinetics are theoretical bases for controlling the steelmaking process. Recent advances in reaction thermodynamics and kinetics and their application in numerical simulation are summarized in the present study. In terms of reaction thermodynamics, the main models for calculating the activity of liquid steel are the Wagner interaction parameter formalism (WIPF), the unified interaction parameter formalism, and the associate model. At present, the WIPF model is still the most widely used model for calculating liquid-steel activity, but with the development of new steel grades, the universality of the WIPF model has been challenged. An urgent need exists to develop a new model for liquid-steel activity calculations and to supplement it with new data. The main models for calculating slag activity are molecular theory, ionic theory, the regular ionic solution model, the modified quasi-chemical model (MQM), and ion and molecular coexistence theory (IMCT). The MQM and IMCT models are the most widely used for calculating slag activity. Reaction kinetic models such as the multicomponent coupled reaction model, the effective equilibrium reaction zone model, and the unreacted nucleus model can accurately predict changes in the molten steel, slag, and nonmetallic inclusions during the steelmaking process. However, the mass transfer coefficients in these kinetic models are mostly determined using empirical equations, which cannot accurately characterize the kinetics in different reactors. To address this problem, the three-dimensional distribution of the molten steel composition and its time evolution during the iron desulfurization process in Kambara reactor and the steel decarburization process in Ruhrstah-Hereaeus reactor were revealed by coupling the reaction kinetics with three-dimensional numerical simulations. However, no mature three-dimensional numerical simulations are available for multiphase and multidimensional reactions with the integrated consideration of molten steel, slag, inclusions, refractory materials, and alloys, which requires further in-depth study.