Based on the first law of thermodynamics and second law of thermodynamics, using enthalpy-exergy compass, the thermodynamic analysis of the waste heat recovery system using different methods to recover the sensible heat of molten BF slag was studied. The results show that the heat efficiency of physical methods is 76.9%, and the exergy efficiency of recovery as steam is 34.2%; the heat efficiency of combined methods is 92.2%, and the exergy efficiency is above 60%. The heat efficiency and exergy efficiency of combined methods are higher than that of physical methods. On the promise of making comprehensive consideration for the exergy efficiency and the reaction condition, whether or not to consider the use of catalyst, the consumption of reactant and the amount of product, the C-CO2/H2O reaction are selected as the best reaction. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.